Armalite AR-10 (USA)

The original AR-10 of the late 1950s. Note the three-prong flash hider and a bayonet lug under the barrel

AR-10(T) - a target grade version of the "new" AR-10, with Picatinny-type rail instead of the carrying handle, and the match barrel

The original AR-10, partially field-stripped. The similarity to the latter AR-15/ M16 rifles is obvious

Caliber: 7,62mm NATO (7.62x51mm)

Action: Gas operated, rotating bolt

Length : 1016 mm

Barrel Length: 508 mm

Weight: 4.31 kg empty, without magazine and sling

Magazine: 20 rounds

Rate of fire: 700 rounds per minute (original military version)

TheAR-10 rifle, designed by the Eugene Stoner at the Armalite division of the Fairchild Engine and Airplane Corp, seen no significant success at the time ithad been introduced, but it still had some historical significance since the AR-10 served as a basis for the further development of the much more successful AR-15/ M16 series rifles. Basically, earliest AR-15 prototypes were no more than a scaled-down AR-10. The AR-10 was intended for the US Army trials for a newbattle rifle, to replace the venerable M1 Garand.AR-10, with the first prototype built in 1955, came too late for these trials,and was too unconventional for conservative minds in the US Army, and consequently lost the trials to the T44 rifle, which was adopted in the 1957 as the M14. The AR-10 was ready for mass production by the 1960, but very few were made in USA. A manufacturing license had been sold to the Dutch company Artillerie Inrichtingen. Only Sudan and the Portugal apparently bought some AR-10 rifles for their military, and the production of the AR-10 had been ceased in the early or mid-1960s, with only about 10 000 military AR-10 being ever made.

Some two or three decades later, the reorganized Armalite company brought the modified AR-10 rifle back to civilian and police markets. Unlike the original AR-10, the new AR-10B is a semi-automatic only rifle, and it is available in four basic versions. The AR-10B itself is more or less a copy of the original AR-10, with the similar brown plastic furniture and short buttstock, and with the trigger-like charging handle under the carrying handle. The other three models look more like the scaled up M16A2 derivatives,with the same A2-style furniture, sights, and M16-type charging handles. TheAR-10A2 has all the A2 furniture and options, while the AR-10A4 has the"flat-top" style receiver with the Picatinny rail instead of the carrying handle. The AR-10(T) is a target grade rifle, with match barrel and trigger andA4-type flat-top receiver.

Technically, the AR-10 differs very little from its direct derivative, the AR-15/M16, so for a complete description please refer to the AR-15 / M16article on this site.

Armalite AR-18 assault rifle (USA)

Original AR-18 assault rifle, made by the Sterling Armaments of UK

The "reincarnated" AR-180B of recent manufacture. Semi-automatic onlyand with plastic lower receiver with integral pistol grip

Schematic view of the AR-18 (from the original Armalite patent, issued in 1968)

Caliber: 5.56x45 mm (.223 Remington M193)

Action: Gas operated, rotating bolt

Overall length: 940 mm (738 mm with folded stock)

Barrel length: 464 mm

Weight: 3.09 kg with empty 20 rounds magazine

Magazine capacity: 20, 30 or 40 rounds

The AR-18 rifle had been developed by the Armalite company (USA) by the George Sullivan, Arthur Millerand Charles Dorchester in the early 1960s. This rifle was designed for the international military market as a replacement for the AR-15 project, which had been sold to the Colt in 1959 by the Armalite's parent company, Fairchild Aircraft and Engine Corp. The AR-18 was designed as a competitor to the AR-15, which could be made at much less expenses and on simplified machinery, with the view to sell the manufacturing licenses for AR-18 to the third world countries. The AR-18 was a really successful design from a technical standpoint, but it come out too late to compete with both officially accepted and adopted AR-15/M16 rifle of American origin and already widespread AK-47 rifle of the Soviet origin. The Armalite company by itself made very few specimens of this rifle.The manufacturing license was consequently sold to the British company Sterling Armaments Co and to the Japanese company Howa Machinery co, but all three companies produced hardly over 20 000 rifles total, and the production of the AR-18 was ceased circa 1979 for some 20 years. It was originally available in the military AR-18 (selective fire) and AR-18S (selective fire, with short barrel) versions,and in AR-180 semi-automatic only version. But in the year 2001 the Armalite company resurrected the AR-180 design, in somewhat modified form. New rifle,intended mostly for the civilian and law enforcement markets, featured the same AR-18 layout and action, but discarded the stamped steel lower receiver andreplaced it with the plastic lower, with AR-15-compatible magazine housing and AR-15-type trigger unit, which allowed for wider spare parts availability. Theoriginal folding buttstock and flash suppressor are replaced with the plastic fixed buttstock of the same shape and the muzzle recoil compensator, to complywith the current US firearms laws. The price of AR-180B is slightly lower than of the similar basic AR-15 type rifle, and the available user reports aboutAR-180B are generally quite positive.

The most interesting point about the AR-18 is that, while being a commercial failure, it served as a platform forsome further development, which took place in various countries. First, the AR-18 design obviously served as a starting point for the ill-fated British SA80/ L85 bull-pup assault rifle, which can be loosely described as a bullpup-ed and weakened AR-18. Second, the AR-18 served as a starting point for theSingapore SAR-80 assault rifle, designed by the Chartered Industries of Singapore with the help of the George Sullivan (who designed the AR-18 itself). And third, the relatively new German Heckler - Koch G-36 assault rifle bears a lot of similarity internally to the AR-18.

Technical description.

The AR-18 is a gas operated, magazine fed, air cooling selective fire rifle.The gas action features a short piston stroke, rotating bolt locking mechanism.The gas chamber and piston are located above the barrel, and the piston has the cupped head and its own return spring. The square-shaped bolt carrier is mounted inside the receiver on two guide rods, with each rod carrying its own return spring. Both rods are linked by the special end plates so the whole bolt / boltcarrier / return springs / guide rods assembly can be removed from the rifle as a single unit, which greatly simplifies the field maintenance. The rotating bolt is somewhat similar in construction to the AR-15 bolt, and is rotated by the bolt pin, which is engaged in the curved cam track, cut in the bolt carrier. The charging handle is fixed to the right side of the bolt carrier and reciprocates when gun is fired.

The receiver is made from stamped sheet steel and consists of two parts - upper and lower. Both halves of the receiver are hinged one to another at the front of the receiver. The upper and lower parts are interlocked by the rear ends of the bolt carrier guide rods. AR-18 is field stripped by pressing the guide rods forward by the special lever at the rear of the receiver, then by the folding the lower receiver down and forward.

The controls consist of the trigger, safety - fire mode selector at the left side of the receiver (similar to one found on AR-15 / M16 type rifles), and the boltstop. The available fire modes are single shots and full auto, or only single shots in AR-180 and AR-180B.

The forearm, the pistol grip and the buttstockare made from black plastic. The buttstock folds to the side to save the space,if required, and AR-15 can be fired with butt folded. The sling attachment points are located on the barrel, just ahead of the forearm, and at the butt ofthe pistol grip, so the sling position is not affected by the position of the foldable buttstock.

The sights consist of the hooded front post and the"L"-shaped flip-up diopter rear, also protected from sides by large"dog ears". Each AR-18 also was fitted with the scope mount at the top of the receiver by standard.

ColtM4 and M4A1 carbine / assault rifle (USA)

Colt M4 carbine, current issue model with removable carrying handle, left side

Colt M4 carbine, current issue model with removable carrying handle, right side

Colt M4 carbine, old version with fixed M16A2-style carrying handle and M203 grenade launcher

Colt M4 carbine, current issue model with Trijicon ACOG telescope sight installed over the integral Picatinny rail and M203 grenade launche mounted onto the RIS forend.

Colt M4 carbine with Mk.18 CQBR upper receiver, fitted with Aimpoint red-dot sight and additional back-up iron sights (BUIS)

image: THOR Global Defense Group

Click here to see the the SOPMOD M4A1 kit (54 Kb JPEG, will open in new window)

Caliber: 5.56mm NATO

Action: Gas operated, rotating bolt

Overall length: 838 mm (stock extended); 757 mm (stock fully collapsed)

Barrel length: 370 mm

Weight: 2.52 kg without magazine; 3.0 kg with magazine loaded with 30 rounds

Rate of fire: 700 - 950 rounds per minute

Maximum effective range: 360 m

The Colt company developed various carbine versions of the basic AR-15 / M16 rifle since 1970s. These carbines were intended for all markets - military, law enforcement, civilian. US Military (and some other armies, most notably - Israeli Self-Defense Forces) had adopted the Colt CAR-15 Commando and XM-177 carbines during the 1970s and 1980s. But early in 1990s the old idea of replacing the pistols in the hands of the troops with some more effective, shoulder fired weapon, rise again in the heads of the US Military. In fact, this idea can be dated back to the US M1 Carbine of 1941, but good ideas never die. So, in the 1994, US Army adopted the Colt Model 720 selective-fire carbine (basically, a shortened M16A2 rifle), as the US M4 Carbine. This weapon was intended to replace in service some M9 pistols, as well as some aged M3A1 submachine guns and some M16A2 rifles. New weapon was much more handy and comfortable to carry, than the long M16A2rifle, so the US Special Operations Command (SOCOM) put its eye on the M4 as a possible universal weapon for all Special Operations community. For this purpose M4 was latter modified with the M16A3-style flat-top receiver with integral Picatinny-type accessory rail instead of the M16A2/M4-type integral carrying handle. This modificatin retained the M4 index. The only difference between the M4A1 and M4 is that its trigger unit of M4A1 is modified to fire full-auto instead of the three shots bursts in M4. Specially for the SOCOM M4A1s US Naval Surface Warfare Center developed a SOPMOD M4 kit, that consisted of the M4A1 carbine equipped with Rail Interface System (RIS) instead of the standard handguards. The kit also includes a variety of the add-on goodies, such as various sights (ACOG 4X telescopic, ACOG Reflex red-dot, detachable back-up open sights), laser pointers (visible and infra-red), detachable sound suppressor (silencer), modified M203 40mm grenade launcher (with shortened barrel and improved sights). The kit also included a detachable front grip and tactical light.

At the present time, the M4 carbine is used as a front-line weapon by US Army, Marine Corps and SOCOM operators in Iraq and Afghanistan. Combat experience with thos weapon resulted in update program, which will, as of now (mid-2010) following steps. First, Army wanted to install heavier barrel to allow more sustained firepower, combined with full-automatic mode of fire instead of 3-round burst, and ambidextrous safety/selector switch. Second stage will see improved rail adapter and a new, improved bolt carrier, and a possible third stage will include change of operating system (most probably, from direct gas to the gas piston).

At the present time, the Colt company still is the the prime M4 carbine manufacturer for US Armed forces, but many other companies build similar "milspec" weapons for other US and foreign customers, such as government and private security organizations, law enforcement etc. To name just few, M4-type carbines are manufactured by Bushmaster Firearms, Olympic Arms, THOR Global Defense Group and others

Technical description.

The M4 carbine differs from the M16A2 rifle only by having a shorter barrel and a telescoped, 4-position buttstock. The M4A1 is a similar modification of the M16A3 rifle, so for general technical description please refer to the M16 article on this site.

M14 rifle / Mk.14 Mod.0 Enchanced Battle rifle (USA)

T37 experimental rifle.

M14 rifle, military issue version with fire mode selector switch installed.

Close-up view on the controls of the military M14 rifle, including fire mode selector switch (on receiver above the trigger).

M14A1 "Squad automatic weapon". Note the different stock with folding forward grip and detachable bipod.

US Navy's Mk.14 Mod.0 Enchanced Battle rifle, a heavily modified M14 automatic rifle.

M14 Designated Marksman Rifle (DMR), as issued by US Marine corps. This particular rifle is fitted with quick-detachable sound moderator (silencer).

M14S semi-automatic rifle, as made in China by Poly Technologies.

Springfield M1A semi-automatic rifle with polymer stock and 10-rounds magazine.

Caliber: 7.62x51 mm NATO (.308 Winchester)

Action: Gas operated, rotating bolt

Length: 1120 mm

Barrel Length: 559 mm

Weight loaded: 5,1 kg (6.6 kg M14A1)

Magazine: 20 rounds, detachable box

Rate of fire: 700 -750 rounds per minute

The experience gained by US troops during the Second World war showed that the M1 Garand rifle has a lot of things to be improved. The first was the feeding system with 8-rounds en-bloc clips that does not allowed the refilling of the partially full magazine. Others were excessive length and weight of the rifle. The cartridge used in M1 Garand and known as .30-06 (7.62x63mm) was too long and too heavy, effectively limiting the load of ammunition carried by each soldier. First attempts to improve M1 were made during the war, and numerous experimental modifications in .30-06 were built, mostly using the 20-rounds detachable magazines from Browning BAR M1918 automatic rifle. One of such prototypes was the T20 ("T" means "test") of 1944. T20 was basically the M1 Garand rifle fitted with 20 rounds BAR magazine and with selective fire capability. This prototype latter evolved into the T37 rifle, which had gas cylinder moved back a little and was chambered for newest American prototype cartridge - T65. The T65 was no more than .30-06 case, shortened by 1/2 inch (12 mm), but retaining the original ballistic properties due to modern propellants used. It was slightly lighter and cheaper to made than .30-06, and has long effective range and good potential for accuracy, both desired by US Army. The idea of truly intermediate round was not acceptable to the US Military at that period. In the early 1950s T37 evolved into the T44 experimental rifle, which featured redesigned, self-regulated gas system with short stroke gas piston. Further development and tests lead to the slightly modified T44E4 and T44E5 (heavy barreled squad automatic weapon) prototypes, which were finally adopted by US Army as M14 and M15 rifles in the 1957. The M15, a heavy barreled weapon, however, was never brought into production. It must be noted that T44E4 was extensively tested against the only other entree in the US trials, the T48 rifle (Belgian FN FALrifle made under license in USA by H&R Inc.). Both rifles passed the trials with equally high results, but US finally settled on the T44 because it was slightly lighter, similar to M1 Garand in manufacturing and operation, and, above all, a "Native American" design.

The contracts to produce M1 rifles were issued to some US companies, such as Thompson-Ramo-Wooldridge (TRW Inc), Harrington and Richardson Arms Co (H&R), Winchester-Western Arms Division of Olin Mathieson (Winchester) and Springfield Armory Inc (Springfield). Production was ceased by US Government in 1964, with some 1 380 000 weapons made. The termination of the production was the result of combat experience in the SE Asia, particularly in Vietnam. The M14 was too long and too heavy to be carried all day long in hot and wet climate. The 7.62mm NATO ammunition was too heavy, limiting the amount of ammunition carried by soldiers on patrols. The selective fire capability was mostly useless, since the M14 was way too light for powerful cartridge it fired, and climbed excessively when fired in bursts. In fact, most of the M14s were issued to troops with fire selectors locked to semi-automatic mode, to avoid useless waste of ammunition in automatic fire. The squad automatic version, known as M14E2, also was not too successful in its intended role. As soon as those deficiencies of the M14 became obvious for US Army Command, they started the search for lighter rifle, and finally settled on the Colt/Armalite AR-15 5.56mm assault rifle, adopting it as the M16A1. M14 was replaced as a first line weapon in the late 1960s, but is still used in small numbers by US Navy. It also served as a platform to build M21 Sniper rifles. Semi-automatic only versions of the M14 rifle are commercially manufactured for civilian and police markets by the Springfield Armory Inc since 1974 under the name of M1A. Some other US companies are assembling the M14-type semi-automatic rifles using military surplus M14 parts kits. Beginning in the early 1970s thousands of M14 rifles were given to several nations under military aid programs. In the 1990s alone, over 100,000 of these rifles have been given away to Estonia, Latvia, Lithuania, the Philippines, South Korea, Taiwan, and Turkey. In USA, for some time M14 was mostly relegated to Honor Guard and similar duties, but during recent campaigns in Iraq and Afghanistan many old M14 rifles were withdrawn from warehouses, dusted off and issued to troops in the field to improve range and lethality of troops armed with 5.56mm weapons. Some M14 rifles are issued as is, some are fitted with new telscope sights to serve as a para-sniper / designated marksman rifles (concept similar to Russian SVD rifle). US Marine Corps also re-issued M14 rifles for use in Designated Marksman role (DMR), and those rifles are fitted with newly made polymer stocks with adjustable buttstocks and pistol grips, and other accessories such as detachable bipods or sound moderators (silencers). Recently US Special Forces, operating under the US Navy flag, stepped forward with the Mk.14 Mod.0 Enchanced Battle rifle, which is an M14 fitted with many new commercially available parts, new stock with adjustable butt and plenty of Picatinny rails, and new accessories such as noise suppressors and optical equipment. The Mk.14 Mod.0 EBR is currently being used by US Navy SEAL's and possibly some other special operation forces within US Military.

In general, the M14 was a comtroversial weapon. It had the accuracy and range of the "old time" military rifles, but was too long, heavy and lacked the automatic fire firepower of a true assault rifle, often required in the modern close combat. Nevertheless, it was a reliable and powerful weapon, often favored by users for high lethality, long range and good penetration - features much appreciated by US soldiers during recent operations in Afghanistan and Iraq.

The M14 is a gas operated, magazine fed, selective fire (originally) design. The gas system is located under the barrel, and has a short stroke (about 1 1/2 inch - 37 mm) gas piston which operates the M1 Garand style action rod. The gas system features an automatic gas cutoff feature, which limits the amount of gases used to operate the weapon. The rotating bolt is quite similar to one found in M1 Garand but it has a roller instead of the simple lug, which connects the bolt to the operating rod. The fire mode selector is located at the right side of the receiver, above the trigger, and could be removed if rifle should not be fired in bursts, or re-installed if required. The rear receiver bridge features the stripper clips guides, so the detachable magazine could be refilled in place by using standard stripper clips. The bolt stop device is incorporated into the left wall of the receiver and holds the bolt open when last round from the magazine is fired. The safety switch is similar to M1 Garand and is located at the front of the triggerguard. Standard sights consist of the blade front sight with two protective "ears" and diopter-type adjustable rear sight, mounted on the rear of the receiver. Barrel is equipped with long flash suppressor. To be used in selective fire mode, M14 can be equipped with light detachable bipod. The M14A1 Squad Automatic rifle differs from M14 in the following: the fire selector is always installed. The standard wooden single-piece stock with semi-pistol grip is replaced by the "straight line" wooden stock with separate pistol grip and with folding front grip under the forearm. The hinged shoulder rest is attached to the buttplate. Special removable muzzle jump compensator is fitted to the barrel, as well as lightweight bipod.

Armalite / Colt AR-15 / M16 M16A1 M16A2 M16A3 M16A4 assault rifle (USA)

First model ArmaLite Ar-15 rifle, with original 25-round magazine. Note the position of charging handle

Early model M16 rifle, as used by US AF, with early military issue 20-round magazine. Note the three-prong flash hider and the lack of forward assist

M16A1 rifle with 30-round magazine and bayonet, right side

M16A1 rifle with 20-round magazine, left side

M16A1 rifle with M203 40mm grenade launcher

M16A2 rifle with 30-round magazine, right side

M16A4 rifle with 30-round magazine and carrying handle installed over the Picatinny rail, right side

M16A4 rifle with RIS (Rai Interface System) installed around the barrel, and the Aimpoint red-dot signt installed on the rail instead of the detachable carrying handle

See the M16A1 field-stripping

See typical markings and controls on the M16A1 rifle

See M16A3 receiver X-ray image. Aluminum parts are in blue color, steel parts are black

Exploded view of the AR15

The story of the M16 rifle is one of most turbulent and controversial episodes in the whole history of US small arms. It was hastily adopted as an iterim measure, but eventually soldiered on to see more than 40 years of active service. Its early days were full of controversy and scandals, its present is full of competition, but it appears that this weapon will serve with American armed forces and abroad for at least several years (if not decades) more. Today it can be considered as adequate military rifle with good current service record. Obviously, it is far from being ideal, but no rifle in the world is ideal as well. We only have to see, if the American armed forces will eventually step up and produce a better rifle and / or cartridge in a foreseeable future.

The origins of the M16 rifle lay in the research, conducted soon after the Korean war by Operations Research Office (ORO), founded at Hopking University and sponsored by US Army. Among the reports, produced by the ORO, two are most significant in this respect, the so called Hall and Hitchmann reports. One report stressed the fact that most hits, achieved by soldiers in battle, were made at relatively short ranges (within 300 meters) and, mostly, at random. This significantly undermined the obsession for long-range aimed fire, promoted by the Army. Second report suggested, that the most effective way to increase the probability of hits in the battle is to fire multiple small caliber, high velocity projectiles with controlled dispersion instead of one, relatively heavy and large projectile as used in conventional rifles at the time. The latter concept initiated so called "Project SALVO", which was conducted between 1952 and 1957 to develop a proper concept of a new, small bore military rifle. There were several basic concepts, including different projectile types (standard bullets or small, arrow-like finned projectiles known as "flechettes"), fired by score from single round (to achieve 'shotgun' effect) or in rapid bursts of several rounds, each firing single projectile. Eventually, army selected the concept of weapon, firing controlled bursts of single flechettes (steel arrows with body diameter of amout 1.5mm) to go ahead, and called this APHHW - All Purpose Hand Held Weapon, later renamed to SPIW - Special Purpose Individual Weapon. In teh mean time, some elements within Army also sponsored a more conventional approach to the same problem, and oredered development of conventional automatic rifles, firing ordinary small-caliber bullets. During late 1950s and early 1960s there was a lot of experimentation and development in regard of new ammunition, optimal calibers and rifle designs. The problem was, that widely promoted SPIW program seemed to have no end, and the recently adopted "full-power" 7.62mm M14 rifle faced serious production problems.

Enter the Armalite. In the year of 1957 The US Army requests the Armalite Division of the Fairchild Aircraft Corp to develop a rifle of .22 caliber, lightweight, select-fire, and capable to penetrate the standard steel helmet at 500 meters. The Eugene Stoner, then a designer at the Armalite, began to develop this rifle, based on his earlier design, 7.62mm AR-10 battle rifle. At the same time, experts at the Sierra Bullets and the Remington, in conjunction with Armalite, began do develop a new .22 caliber cartridge, based on the .222 Remington and .222 Remington Magnum hunting cartridges. This development, initially called the .222 Remington Special, was finally released as .223 Remington (metric designation 5.56x45mm). Next year Army tests new rifles, known as Ar-15, and rejects these in favor of the M14. Feeling that the Ar-15 rifle has poor chances to compete with the recently adopted M14 in the US Military, in 1959 the Fairchild Corp, a parent company of the Armalite, sells all rights and manufacturing documentation for this rifle to the Colt's Patent Firearms Manufacturing Company, which had long-time relations with US Military and proven track of selling military guns both in USA and abroad. Colt instantly begins aggresive marketing campaign for the new rifle, stressing its accuracy, low recoil, light weight and modern design. In the 1962, US DoD Advanced Research Projects Agency (ARPA) purchases 1000 AR-15 rifles from Colt and sends those rifles to the South Vietnam, for field trials. Same year brings glowing reports about the effectiveness of the new "black rifle", used by South Vietnamese forces.

Following the delays in introduction of the ill-fated 'next generation' SPIW system and production troubles with M14, in 1963 Colt receives contracts from US Government for 85 000 rifles for US Army (designated as XM16E1) and for further 19 000 rifles for US Air Forces (designated M16). The US AF M16 was no more than an AR-15 rifle with appropriate markings. The XM16E1 differed from AR-15/M16 by having an additional device, the so called "forward assist", which was used to manually push the bolt group in place in the case of jams. Next year US Air Forces officially adopted new rifle as M16. Same year US Army adopted the XM16E1 as a limited standard rifle, to fill the niche between discontinued 7.62mm M14 rifle and the forthcoming SPIW system (which newer got past the prototype and trial stages).

With rapidly growing presence of US troops in Vietnam, in 1966 US Government makes the first large purchase of the Ar-15 / M16 rifles, ordering 840 000 rifles for US Armed forces, worth almost $92 millions, and in 1967 US Army officially adopts the XM16E1 rifle as a standard "US Rifle, 5.56mm, M16A1".

During immediately following years, a number of negative reports apears from Vietnam. M16A1 rifles, issued to US troops in the Vietnam, severely jammed in combat, resulting in numerous casualties. There were some causes for malfunction. First of all, during the introduction of the new rifle and its ammunition into the service, US Army replaced originally specified Dupont IMR powder with standard ball powder, used in 7.62x51mm NATO ammunition. The ball powder produced much more fouling, that quickly jammed the actions of the M16 unless the gun was cleared well and often. It also had different pressure curve, resulting in increased stress on operating parts of the gun. This pitifully combined with the fact that the initial M16 rifles were promoted by the Colt as "low maintenance", so, for the sake of economy, no cleaning supplies were procured for new M16 rifles, and no weapon care training was conducted fro the troops. As a result, soldiers did not knew how to clean their rifles, and had no provisions for cleaning, and things soon turned bad. Another cost-saving measure on the part of the Army was to give up with cromium plation of the barrel bore and bolt group, which made these parts much more sensitive to corrosion and rust that originally designed.

After several dramatic reports in US press and Congressional investigation of the troubles, several actions were taken to remedy the problems. The 5.56mm ammunition was now loaded using different powders that produce much less residue in the gun action. The barrel, chamber and bolt of the rifles were chrome-lined to improve corrosion resistance. Cleaning kits were procured and issued to troops, and a special training programs were developed and conducted ever since. Earliest cleaning kits could be carried separate from rifle only, but since circa 1970 all M16A1 rifles were manufactured with the containment cavity in the buttstock, that held the cleaning kit. At the same time (circa 1970) the new 30 rounds magazines were introduced into service instead of the original 20 rounds ones, to equal Soviet and Chinese AK-47 assault rifles, which had 30-rounds magazines from the very beginning.

Therefore, by the end of the US involvment in Vietnam war, the M16A1 rifle eventually became more or less mature. It gradually replaced older rifles in US service, and also influenced the work on the small-caliber ammunition and automatic firearms in other countries, including the USSR. This work culminated in the NATO trials, held in 1977 - 79, with intent to adopt a small-caliber, high-velocity cartridge to replace the potent, but somehow overly powerful 7.62mm NATO round as standard infantry rifle ammunition for the whole NATO organisation. Not surprisingly, the winner of the trials was the american 5.56x45mm cartridge, although in a version loaded with Belgian SS109 bullet, which provided better long-range ballistics than the original US 5.56mm M193 ammo.

In 1981, Colt developed a variation of the M16A1, adapted for the SS109/5.56mm NATO cartridge, and submitted it to the military trials as the M16A1E1. This rifle differed from the M16A1 by having the heavier barrel with faster 1:7 rifling, a different type rear sights (adjustable for both range and windage), round handguards instead of triangular ones, and by replacing the full-auto fire mode with the burst (limited to 3 rounds per trigger pull), to preserve the ammunition. It was officially adopted by US DoD as the "US Rifle, 5.56mm, M16A2" in 1982, which still is the primary infantry rifle for US Armed forces and a number of other armies and law enforcement organizations.

The development of the M16 rifle continued. By the mid-1990s, Colt, at the request of the US Special Forces, produced a carbine version of the M16A2, designated M4. This carbine traces its roots back to the 1960s vintage Colt CAR-15 carbine, but has several improvements. Actually, it was the M16A2 rifle, fitted with a shorter barrel and handguards, with the gas port moved back. The fixed buttstock was replaced by a retractable telescoping buttstock, originally designed in the mid-1960s by a Colt employee, Robert E. Roy for the Colt “Commando” carbines. The M4 was supposed to become the standard US Special Forces rifle, and could be fitted with the standard M16A2-type bayonet and the M203 40mm grenade launcher.

By 1996, the two newest versions of the M16 appeared, the M16A3 and M16A4. These differ from the M16A2 by having a removable carrying handle, with the upper receiver being fitted with a Picatinny-type accessory rail. Otherwise the M16A4 is similar to the M16A2, while the M16A3 also replaced the infamous three-round burst mode with a full auto mode. The key advantage of both the M16A3 and A4 rifles is the ability to quickly mount and re-mount a wide variety of optical, red dot or night vision / IR sights with MIL-STD 1913 (Picatinny-type) compatible mounts. The M4 carbine was also upgraded to “flat top” configuration, which is now standard.

The M16 is still a general-issue rifle with the US Armed forces. It is also widely used by the US Law Enforcement agencies, either in military form (for example, the LAPD had some M16s, retired from the Army), or in "civilian" semi-automatic only form. The AR-15 style rifles are made in the USA by at least a dozen large companies, such as ArmaLite, Bushmaster, Colt, FN Manufacturing, Hesse, Les Baer, Olympic, Wilson Combat, and by a number of smaller companies, many of which assemble their rifles from components made by other major manufacturers. M16-type rifles are also manufactured outside the USA, most notably in Canada, by Diemaco Co (now Colt Canada). China also makes some AR-15 type rifles at the NORINCO state factories, known as CQ. M16 rifles are used by many foreign military groups, most notably the British SAS, who preferred the M16 over the infamous L85A1 rifle, and by many others.

At the present time almost all of the initial flaws of the M16 have been removed and it is considered among the best assault rifles in the world. While its reliability in harsh conditions cannot match that of its main rival, the Kalashnikov AK-47 and AK-74, it is still a quite reliable weapon, especially when well maintained. It is also comfortable to fire and quite accurate.

It must be noted that during recent operations in Afghanistan and Iraq (2002 and 2003, respectively), there were several controversial complaints about the effectiveness and reliability of the M16A2 and M4 rifles. It seems that most complaints about the reliability of the M16A2 rifles came from inadequate troop training and the resulting improper handling of the rifles. The M4 carbines are a somewhat different story, since the problems can be partially traced to the shortened gas system, which now operates at higher pressures, thus more violently. The M4 also rapidly overheated. Another general complaint was about the poor effectiveness of the standard M855 ammunition, which lacked stopping power especially from shorter M4 carbine barrels. To partially cure this problem, the US SOCOM recently issued a new type of 5.56 mm ammunition, the Mk.262 mod.0, which is loaded with heavier Sierra Match King bullets, weighing 4.99 gram compared with the 4.0 gram bullet in the M855 cartridge. The most recent experience also clearly showed the excessive length of the M16A2 rifles, which are too clumsy for motorised troops, riding in cars, armored carriers and helicopters. At the present time, many M16A2 rifles are being replaced in the hands of US troops with more compact and maneuverable M4A1 carbines.

One of the key advantages of the Stoner design, that must be especially stressed, is the extreme flexibility of the construction. At the present time the interchangeable complete upper receiver assemblies ("upper" in short) are available in various barrel lengths and profiles (from 7 to 24 inches long, slim and heavy), in dozens of rifle and pistol calibers (from tiny but fast .17 Remington and up to monstrous .458 SOCOM, and from .22LR and 9mm Luger up to mighty .50AE). Special, manually single-shot uppers are commercially available in the extremely powerful .50BMG (12.7x99mm) caliber. Various "lower receiver" assemblies offer a broad variety of trigger units, buttstocks and other options. This advantage is viable for both military (especially Spec Ops), Law Enforcement, and civilian applications, as it allows to tailor any particular AR-15 type rifle to the current situation and tactical needs.

M16 / AR-15 Technical description

The original AR-15 rifle is a gas operated, selective fire, magazine fed weapon. Every rifle from the M16 family is generally the same, but most civilian AR-15 type rifles are semi-automatic only.

The heart of the AR-15 is the direct gas system, developed by the Eugene Stoner in the early 1950s. This system uses no conventional gas piston and rod to propel bolt group back after the shot is fired. Instead, the hot powder gases are fed from the barrel and down to the stainless steel tube into the receiver. Inside the receiver, the rear end of the gas tube enters into the "gas key", a small attachment on the top of the bolt carrier. The hot gases, through the gas key, enter the hollow cavity inside the bolt carrier, and expands there, acting against the bolt carrier and the collar around the bolt body. The pressure of the gases causes the bolt carrier to move back against initially stationary bolt. The linear rearward movement of the carrier initially transferred into the rotation of the bolt, via the cam slot in the bolt carrier and the cam pin, attached to the bolt, that followed the slot. As soon as the bolt is rotated to unlock from the barrel, the bolt group continues its rearward travel under the inertia and the residual pressure in the barrel, extracting the spent case and compressing the buffer return spring, located in the buttstock. The forward movement of the bolt group first strips the fresh cartridge from the magazine and, on the final stage of the movement, rotates the bolt to lock into the barrel extension. The bolt has 7 radial locking lugs, eight lug is located on the extractor claw. Since the introduction of the XM16E1 rifle, the forward assist device is used on all military and most civilian AR-15 type rifles. This device consist of the spring-loaded button with internal claw, that engages the serrations on the right side of the bolt carrier to push it forward, if the pressure of the return spring is insufficient to do so (for example, due to the fouling inside the receiver or chamber). The rifle will not fire unless the bolt is locked and the bolt carrier is in its forwardmost position. The bolt carrier and the bolt itself are chrome-plated. Another feature of the AR-15 type rifles is the bolt catch device, that locks the bolt group in the open position when the last round is fired. To release the bolt group one must push the button, located at the left side of the receiver, above the magazine. The "T"-shaped cocking handle is located at the rear of the receiver, above the buttstock, and does not reciprocate when gun is fired.

The trigger/hammer group is basically similar to one, found in M1 Garand rifle, and, actually, traces its roots back to the early 1900s, when the great John M. Browning developed his famous Auto-5 semiautomatic shotgun. This basically consists of a hammer, a trigger, a disconnector, a full auto sear and some springs. The fire selector / safety switch is located at the left side of the receiver, above the pistol grip, and is easily operated by the right hand thumb. This switch has 3 positions: "safe", "semi" (single shots), and "auto" (full automatic on M16A1 and M16A3 rifles) or "burst" (3 rounds bursts, on M16A2 and M16A4). In the latter case (on the M16A2 and M16A4 rifles), the trigger unit also includes the ratchet device to count the shots fired.

The ejection port is located at the right side of the receiver, and is closed by the spring-loaded dust cover, which automatically pops open when bolt carrier is pulled back. The M16A2 also featured the spent case deflector - a triangular bulb on the receiver, just behind the ejection port, that allows the gun to be safely fired left-handed.

The M16 is fed using box magazines. Earliest magazines were made from aluminum and held 20 rounds. Circa 1970 the new, 30 rounds magazines were introduced into service and these magazines are still in service now. An extremely wide variety of magazines available on the commercial marked, starting from the "US post-ban" 5 and 10 round magazines, and up to 40-rounds box, 90-rounds helical, 100-rounds dual drums (Beta-C) and 120-rounds single drums.

The receiver is made from aluminum alloy, and consists of two parts - "upper receiver" and "lower receiver" (sometimes referred simply as "upper" and "lower"). Most receivers are made from aluminum forgings by machining, but some commercially available receivers are made from aluminum castings with final drilling and machining. The upper and lower receivers are linked by two cross-pins - one at the front (pivot pin), and one at the rear, above the pistol grip (takedown pin). To field strip the AR-15, one must push the rear pin to the right as far as it will go, and then hinge the upper receiver around the front pin. This will allow the bolt group and the carrying handle to be removed from the upper receiver. For further disassembly, the front pin also must be pushed out, and the upper and lover receiver can be separated. The key benefit of this design is the great flexibility - if all components available are made to the same specifications (in most cases they are), one can easily swap various upper receivers on one lower receiver and vice versa. Since the complete "upper" module consist also of the bolt group and the barrel with the gas system, one can easily have different barrel lengths, styles (light, heavy, fluted, bull), and even calibers, for one "lower" group, that consists of the lower receiver with the trigger/hammer unit, recoil buffer, pistol grip and the buttstock.

The furniture on military rifles is made from the black plastic, hence the common name "the black rifle". On the early AR-15 and M16A1 rifles, the handguards were of triangular cross-section, and were made from two non-interchangeable parts. On the M16A2 and latter rifles, the handguards are of round cross-section, and have two interchangeable upper-lower sections. The buttstock on the M16A2 is similar in design to one of M16A1, but slightly longer. The one disadvantage of the Stoner system is that it can not be adapted for conventional folding buttstock. Instead, if required, a telescoped stock is used, that allows to shorten the rifle when required by about the half of the length of the standard stock. M16 is usually equipped with sling, and can accept a knife - bayonet, either an old style M7, or a newer style M9. The flash hiders on the earliest AR-15s and M16s were prong-type, with three open slots, but later were replaced with "bird-cage" flash hiders with four (M16A1) or five (M16A2) slots.

Both M16A1 and M16A2 can be equipped with underbarrel 40mm M203 grenade launcher. M203 mount replaces the standard handguards on the rifle and requires a grenade launcher sight to be mounted on the carrying handle.

Standard sights of the M16A1 consist of a protected front post, mounted on the gas block, and of an aperture flip-up rear, with 2 range settings. Rear sights are mounted within the carrying handle and are adjustable for windage. The A2 style rear sight also features an flip-up, dual aperture sights, with one smaller aperture for daylight usage, and another larger aperture for low light conditions. The range adjustments are made by the rotating knob, located just under the sight. The front sight is generally the same as on the M16A1. The M16A3 and A4 rifles have detachable carrying handles with A2 sights, and the Picatinny-type MilStd rail on the top of the receiver, that can accept a wide variety of sighting devices and mounts. The most common military sighting equipment beyond basic iron sights is an Trijicon ACOG low-magnification telescope or Aimpoint or EOTech 1X magnification red-dot sight, often complemented by removable back-up iron sights (BUIS), installed on the same Picatinny rail.

Heckler-Koch HK M27 IAR Infantry Automatic Rifle (USA / Germany)

M27 IAR Infantry Automatic Rifle, as made by HK USA for US Marine Corps

Caliber: 5.56x45mm NATO

Action: Gas operated, rotating bolt

Overall length: 838 - 937 mm / 33" - 36.9"

Barrel length: 420 mm / 16.5"

Weight: 3.6 kg / 7.9 lbs empty

Rate of fire: rounds per minute

Magazine capacity: 30 rounds standard

The IAR - Infantry Automatic Rifle program was originally initiated by US Marine Corps (USMC) in an apparent intent to replace aging M249 SAW light machine guns in their "automatic rifle" (squad automatic) role. USMC sought lighter and more maneuverable weapon, still capable of at least some sustained firepower. Original contenders included guns from FN, Colt and Heckler-Koch, as well as some other, lesser known names. After extensive trials in 2009 USMC finally selected the HK IAR rifle, which, in fact, is no more that heavy-barreled version of their HK 416 automatic carbine (assault rifle), and it hardly looks like adequate replacement for a dedicated squad automatic weapon with belt feed and quick-change barrel. By all accounts, it looks like USMC played the whole IAR trick to get the replacement for their M4 carbines without entering the political hassle and budgetary debates. In May 2010 the USMC representative officially anounced the adoption of the Heckler-Koch IAR as M27 Infantry Automatic Rifle". It is not clear when HK will begin delivery of the M27 rifles, and how much rifles will be delivered to USMC.

The M27 Infantry Automatic Rifle is a gas-operated weapon which is based on the HK 416 assault rifle. It uses short-stroke gas piston that operates the 7-lug rotating bolt, and fires from closed bolt. Receiver is made from high grade aluminum alloy. Combination-type safety / fire selector allows for single shots and full automatic mode. M27 IAR retains all M16-style controls, including last round bolt hold-open device, rear-based charging handle and magazine release button on the right side of the magazine well. M27 IAR is fitted with four Picatinny rails as standard, and may accept any type of sighting devices on STANAG-1913 compliant mounts. Buttstock is of typical M4 design, multi-position telescoped. M27 Infantry Automatic Rifle can feed from standard M16-type 30 round magazines, and will also accept high-capacity double-drum magazines from Beta Co (100 rounds capacity) and Armatac (150 rounds capacity).

Colt CAR-15 / XM-177 Commando (USA)

Colt CAR-15 - earliest version

Colt XM-177E1

Colt Commando (model 733, note M16A2-style brass deflector and forward assist)

Data for current production Colt mod 933 Commando

Caliber: 5.56x45 mm (.223 Remington)

Action: Gas operated, rotating bolt

Overall length: 680 - 762 mm

Barrel length: 292 mm

Weigth: 2.44 kg empty

Rate of fire: 750 rounds per minute

Magazine capacity: 30 rounds (or any other M16 type magazine)

The first carbine version of the M16 assault rifle appeared under the name of CAR-15 in 1965, an was intended for US Special Forces who fought in Vietnam. The original M16 was simply shortened by cutting the half of the lenght of the barrel (from original 20 inches to 10 inches) and by shortening the buttstock by another 3 inches. The butt was plastic and retractable, the handguards were of triangular shape and the flash hider was of original three-prong type. Based on the origunal CAR-15, Colt quickly developed the CAR-15 Air Force Survival Rifle, intended, as a name implied, to serve to downed airplane and helicopter pilots. This version had tubular handguards and metallick tubular buttstock, and fo some reasons the pistol grip was shortened.

Initial combat experience with CAR-15 brought up some problems. First, the carbine was too loud, deafing the firing soldier quite quickly. Second, the muzzle flash was also terrific, blinding the shooter at night and giving avay the position of the shooter to the enemies. Colt partially solved this problem by installing a new, longer flash suppressor. This version, known as the Colt model 609 Commando, also carried new handguards of tubular shape. This model was officially adopted by US ARmy as XM-177E1. This wersion had M16A1-style receiver with forward assist button. In the mid-1967 Colt slightly upgraded the Commando by lenghting the barrel up to 11.5 inches (292 mm), and this version was adopted as XM-177E2.

Later, with the introduction of the M16A2 and M16A3 (flat-top) models, Colt also changed the design of itys Commando line, adding three-burst options and flat-top receivers with Weaver-style rails.

Current Colt Commando carbines (Colt still called these Submachine-guns) are based on either M16A2 or M16A3 receivers, and had 11.5 inch (292 mm) barrels with M16A2-style flash suppressors, and available in either 3-round bursts or full-auto versions. Colt Commando carbines are used by various US Special Forces and by some foreign forces, including Israei ISAYERET.

From the technical point of view, the Colt Commando is similar to contemporary M16 rifle, having same light alloy, two parts receiver, direct gas operated, rotating bolt action, with non-reciprocating charging handle at the rear of the receiver. The telescoping buttstock is made from metallic tube. Due to recoil spring, located inside the butt, the Commando cannot be equipped with side- or underfolding stock withouth some redesigning. Currenly Colt Commando assault carbines are issued with standard M16-type 30 round magazines, but any other M16-compatible magazine can be used, including the 100-rounds Beta-C dual drums.

Stoner 63 weapon system: rifle and carbine (USA)

7.62mm Stoner 62 weapons in light machine gun (top) and rifle (bottom)configurations

photo: SMGLee

5.56mm Stoner 63 weapons, in rifle (top) and light machine gun configurations

photo: SMGLee

5.56mm Stoner 63A rifle, with detachable bipod

photo:

5.56mm Stoner 63 carbine

photo: SMGLee

diagram from original US patent, granted to Eugene Stoner for design of Stoner62 / 63 weapon system

Eugene Stoner, one of designers of M16 rifle, left ArmaLite in about 1961 and joined the Cadillac GageCorp. There he began development of an entirely new weapon system. It was probably the first truly modular system,that consisted of about fifteen subassemblies which could be assembled in any configuration, from an assault rifle and short carbine up to a lightweight or even a general purpose machine gun.First prototypes, chambered for 7.62x51mm NATO ammunition, appeared in 1962,known as Stoner 62. Just a year later Stoner turned out a new system, chamberedfor 5.56x45 M193 US service round, and known as Stoner 63. This system, developed and promoted until the early 1970s, was extensively tested by the US military as the XM22 (Stoner 63A rifle), XM23 (Stoner 63A carbine), and the XM207 (light machine gun with belt feed). The only military application of the Stoner 63 system, however, was the Mk.23 model 0 belt-fed light machine gun configuration, used in limited numbers by US Navy Special Forces and Marine Corps in Vietnam. In general the Stoner system, while having the advantages of modularity and interchangeability of parts and thus great flexibility in tactical use, is too heavy as a rifle, and too expensive and somewhat over-complicated in general. It is also somewhat dirt-sensitive and requires much attention and maintenance.

Overall, some 3,500 to 4,000 Stoner 63 weapon kits were produced between 1962and 1971.

The Stoner 63 is more than just a single firearm; it is a modular kit, which contains about 15 sub-assemblies. Different combinations of those sub-assemblies (barrels, feed units, trigger units, sight units) allow the assembly of various firearms on the single receiver unit.

The stamped steel receiver contains an universal bolt group, with a multi-lug rotating bolt and a long stroke gas piston with gas tube. The receiver also has several sets of mounting points for attachment of all other sub-assemblies and the quick-detachable barrel. In rifle and carbine configuration, the receiver is so orientated that the gas system lies above the barrel and the feed unit mounting points are below the receiver. In all machine gun configurations, either belt or magazine fed, the receiver is turned “upside down”, with the gas system being below the barrel, and the feed unit being above the receiver. In rifle / carbine configuration the Stoner 63 systemutilizes a hammer-fired trigger unit, integral with the pistol grip and triggerguard. This trigger unit allows for single shots and full auto fire, and the gun is fired from a closed bolt only. In machine gun configuration, the trigger unit has no hammer; instead, its sear interoperates with the cut in the gas piston rod, allowing only full automatic fire, and only from an open bolt. The magazine feed unit can accommodate proprietary curved box magazines for 30 rounds, and can be used both in rifle and machine gun configurations. The belt feed unit could be used only in machine gun configurations. Different rear sight units were available for various configurations, with the front sights being mounted on quick detachable barrels.

On earlier Stoner 63 system weapons, the charging handle was located on the right side of the bolt carrier; the safety and fire selector were combined in one control, located on the left side of the trigger unit. On the modified Stoner 63A system, the charging handle was attached to the gas piston rod, and projected from the top in rifle / carbine configuration, or from the bottom in MG / LMG configurations; the safety was made as separate lever at the front of the trigger guard, with the fire mode selector still located on the side of the trigger unit, above the pistol grip. TheStoner 63 system featured a variety of easily detachable fixed or folding buttstocks. The latter were available in a side-folding plastic variety, or in an under-folding stamped steel type, similar to the Kalashnikov AKS / AKMS.

TRW LMR - Low Maintenance Rifle (USA)

TRW LMR (Low Maintenance Rifle) in its final shape, right side, with attached M6 bayonet

TRW LMR (Low Maintenance Rifle) in its final shape, left side, with 30-round magazine attached

Caliber: 5.56x45mm M193

Action: Gas operated, locked by rollers

Overall length: 870 mm

Barrel length: 493 mm

Weight: 3.63 kg loaded

Rate of fire: 450 rounds per minute

Magazine capacity: 20 or 30 rounds

The Low Maintenance Rifle project was initiated by US Army as a result of field experiences, gained through Vietnam war. The standard issueM16 rifle was found to be very sensitive for improper maintenance, and it was decided to look for an infantry rifle, which could work with much less attention paid to routine maintenance, cleaning and lubrication. The one possible niche for such weapons was the "insurgency weapon" for various pro-US (or anti-communist)movements in the third world countries. Development of the LMR project was handled to the US company Thompson-Ramo-Wooldridge (TRW) Inc, and work commence din 1971. Several prototype rifles were built between 1971 and 1973, when US Army decided to stop funding for LMR, as the Vietnam war was over, and M16A1 rifle was considered to be mature enough.

It must be noted that at least one LMR prototype was built for 5.6mm XM216 ammunition that fired saboted sub-caliber flechette projectile. However, most ofLMR rifles were built for then-standard 5.56x45 M193 ammunition.

Required "low maintenance" was achieved by using new and improved corrosion-resistant coatings for all metallic parts, as well as thin layers ofdry lubricants applied to all moving parts. The number of parts was also decreased, compared to the M16 rifle. TRW LMR was simple in use and could be disassembled and re-assembled without any tools.

TRWLMR is gas operated weapon that uses long-stroke gas piston, located at the right side of the barrel. Gas port is located near the muzzle, and gas block serves as a base for front sight. The barrel is enclosed in tubular metallic handguard with oval cooling slots. TRW fired only in full automatic mode, andfrom open bolt. Locking is achieved by a pair of rollers, that engage respective cuts in the barrel extension when in battery. Unlike most other roller-locked designs, LMR bolt had rollers at the top and the bottom, not at left and right.Charging handle was attached to the gas piston rod, and when turned down, locked the bolt in forward position for added safety. Trigger unit and pistol grip were borrowed from US M60 machine gun; manual safety was located at the left side of pistol grip. Magazine (of standard M16 pattern) was inserted horizontally from the left; empty cases were ejected to the right through the ejection port, which has dust cover that opens and closes automatically as gun is fired. Since the LMR was built into so called 'straight'or 'in line' layout, open sight were put onto high bases. front sight was of post type, rear sight was a flip-up diopter with two apertures. LMR combatcapabilities could be further enhanced with addition of light, removable bipod and M6 bayonet, which was attached at the top of gas cylinder, to the right ofthe barrel axis.

Bushmaster M-17s rifle (USA)

Bushmaster M-17s rifle, left side view.

Bushmaster M-17s rifle, right side view, with installed Red Dot sight.

Caliber: 5.56x45 mm (.223 Remington)

Action: Gas operated, rotating bolt

Overall length: 760 mm

Barrel length: 546 mm

Weight: 3.72 kg empty

Magazine capacity: Accepts all M16/AR15 magazines, standard capacity 30 rounds

This interesting weapon started its life in around 1982, when a small Australian company Armstech decided to develop a new assault rifle for Australian army trials. Prototype weapons were produced in a very short amount of time, but Australian army eventually selected for adoption an already established foreign weapon, the Austrian-made Steyr AUG. Nevertheless, Armstech kept developing and produced a series of interesting weapons, all in bullpup layout (and some firing caseless ammunition of indigenous design), but neither went past prototype stage. In around 1990 Armstech went belly up, and rights to the rifle that fired conventional ammunition was sold to another Australian company, known as Edenpine. Further development at Edenpine resulted in SAK 30 prototype, but company found that there's no market for such weapon in peaceful Australia. Therefore, in early 1990s Edenpine found an American company, Bushmaster Firearms Inc, which finalized the prototype and put it into production in 1994, just before the infamous "Assault weapons ban". Bushmaster designated new rifle as M17s and produced it in somewhat limited numbers up until 2005, when it was dropped from Bushmaster products line. It must be noted that demise of Bushmaster M17s was caused mostly by general preferences of American gun market, which is rather shy on bullpups; therefore, Bushmaster company decided to concentrate on much better selling rifles, patterned after Ar-15 / M16 or M4.

The M17s is a self-loading rifle, and thus cannot be classified as a true "assault rifle". Nevertheless it could make a very good paramilitary of home defense weapon; it is also good plinker and all-around compact rifle in .223 caliber, combining rifle-length barrel with carbine-style short overall length.

The M17s rifle is gas operated weapon that uses short-stroke gas piston, located above the barrel. Locking is achieved by rotary bolt with seven lugs; bolt is hosted in massive Ar-18-style bolt carrier, which rides on dual guide rods. The charging handle is somewhat unusual as it forms the rear part of the integral carrying handle, and therefore it is fully ambidextrous. The cocking handle slot on the top of receiver is covered by sliding dust cover. The receiver of weapon is a composite affair, consisting of extruded aluminum upper part and polymer lower part. Upper part houses barrel, gas system and bolt group. Lower receiver is made integral with pistol grip and houses trigger unit and magazine housing. Upper and lower receivers are connected by two push-out cross-pins. Ejection port is made on the right side of the weapon only, and there's no provisions for left-hand ejection. Nevertheless, weapon is more or less ambidextrous in regard to controls, as push-button safety (located at the front of triggerguard) and magazine release buttons are made ambidextrous too. M17s will accept all M16 / Ar-15 type magazines. The top of the carrying handle is fitted with Weaver-style accessory rail which will accept any compatible scope mounts, and also hosts a rudimentary backup open sight.

Ruger AC-556 assault rifle / Mini-14 GB rifle (USA)

Ruger AC556 assault rifle with 30-round magazine. Note the fire mod selector at the rear of receiver, above the trigger

Ruger AC556F assault rifle, with short barrel, 20-round magazine and stockopened

Ruger AC556F assault rifle, with stock folded

Ruger Mini-14/GB "paramilitary" rifle, less magazine

Ruger Mini-14/GB-F "paramilitary" rifle with folding stock, full-length barrel and 30-round magazine. Note lack of fire selector on receiver

Ruger Mini-14 rifle, original version (1980's production) with aftermarket magazine

Ruger Mini-14 "Ranch" rifle of pre-2005 production. Note receiver with integral scope mounts and folding rear sight

Ruger Mini-14 rifle, current version (as made since 2005). Note different front and rear sights and polymer handguard which covers most of the operating rod;

Ruger Mini-30 "Ranch" rifle of current manufacture, with polymer stock

Caliber: 5.56x45mm NATO (.223 Remington); also 7,62x39 M43 in Mini-30

Action: Gas operated, rotating bolt

Overall length: 943 mm (851 / 603 mm for AC-556F)

Barrel length: 470 mm (330mm for AC-556F)

Weight: 2,9 kg empty

Magazine capacity: 5, 10, 20 or 30 rounds detachable box magazines

Rate of fire: 750 rounds per minute (for AC-556 only)

Bill Ruger, one of leading US arms designers of post-WW2 period, begandevelopment of a new semi-automatic rifle circa 1970. The rifle was intended foreither civilian and para-military use; it was patterned after current US issue military rifle, the M14, and was chambered forrelatively new 5,56x45mm (.223 Remington) ammunition. Since its commercial introduction in 1973 the Ruger Mini-14 rifle found wide acceptance among bothcivilian shooters and a variety of police and security forces around the world.For government users, Ruger produced two specialized versions of the basic rifle- the Mini-14GB and AC-556. The former is still a semi-automatic only weapon,but is fitted with protected front sight, flash-hider and a bayonet lug. Thelatter is a selective-fired weapon, and thus can be classified as a true assault rifle. All weapons in the Mini-14 family share same basic design, although thereare differences in certain parts; for example, AC-556 rifles had slightly longer receiver, which hosts the fire mode switch at its rear part.

The first major modification to the Mini-14 family appeared in 1978, when Ruger introduced an all-stainless version of the basic rifle. Until now, all Ruger Mini-14 rifles are available either in carbon or stainless steel versions. In around 1982 Ruger introduced its next civilian modification of the Mini-14,known as the "Ranch" rifle. This version was optimized for use with telescope sight, and thus was produced with integral scope bases on receiver.Ejection mechanism was changed to eject spent cases to the right side, clear of the scope, and rear sight was fitted on the folding base. In 1986, Ruger introduced a Mini-30 rifle, which was same basic weapon but adapted to 7,62x39M43 ammunition of Russian origin. The last change in the Mini-14 line-up appeared as late as in 2005, when Ruger company introduced a new version of theMini-14, which incorporated integral scope bases of the earlier"Ranch" rifles with protected front sight and non-folding diopter rear sight, which has smaller mount that of previous rifles.

In general, Mini-14 rifles are known for their good reliability and durability.Accuracy is usually quoted as somewhat inferior to AR-15(M16)-type weapons, which are very popular in USA; however, Mini-14 rifles are accurate enough for most purposes, and are excellent weapons for hunting,home defense, and general plinking.

Ruger Mini-14 is gas operated, semi-automatic only weapon which uses Garand-typerotary bolt with two lugs. Action is operated by the long-stroke gas piston,which is located below the barrel and is concealed within forend of the stock.The gas piston has cup-shaped head, and is linked to the bolt via Garand-typeoperating rod which runs at the right side of the weapon. Manual safety also patterned after M1 Garand orM14 rifle, and is located at the front of the triggerguard. The selective-fire AC-556 hosts fire mode selection mechanism at the rear of the somewhat lengthened receiver. Fire mode selector is a separate switch on the right side of receiver,behind the ejection port. It has three positions - for single shots, 3-round bursts and full automatic fire.

Standard stock of the Mini-14 is of single-piece type, with semi-pistol grip and separate heat shiled above the barrel. Early Mini-14 rifles had wooden heatshiled which exposed operating rod; military-type Mini-14GB and AC-556 rifles, as well as current production civilian guns, feature polymer heatshields which over most of the operating rod. Over the time, Ruger also produced a folding-stock versions with wooden stock, plastic pistol grip and side-folding metallic shoulder stock. Ruger also makes "all-weather" polymer stocks for Mini-14 and Mini-30 rifles. It also must be noted that there are manyaftermarket stocks for Mini-14 rifles.

Standard sights consist of a blade-type front and adjustable diopter-type rear sight; "Ranch" type rifles also had integral scope mounts on the receiver, which will accept proprietary Ruger scope rings.

Original magazine capacities for Mini-14 rifles were 10 or 20 rounds, but since infamous American "Assault weapons ban" of 1994 Ruger offered civilian Mini-14 rifles with magazines containing only 5 rounds; however, some magazine makers produced after market magazines for Mini-14 and Mini-30 in capacities ofup to 40 (box) and 90 (snail-drum) rounds.

Alliant Techsystems / Heckler-Koch XM-29 SABR / OICW assault rifle (USA)

The left side view on the XM-29 OICW, showing its controls on the sighting unit.

The major components of the XM-29.

XM-29 OICW ammunition - HE (High Explosive) ant TP (target practice) rounds for 20mm unit and KE (Kinetic Energy) 5.56mm NATO round.

Caliber: 5.56 mm NATO (KE) and 20x85mm (HE)

Action: Gas operated, rotating bolt (KE), unknown (HE)

Overall length: 890 mm

Barrel length: 250 mm (KE) 460 mm (HE)

Weight: ca 5.5 kg empty; ca 6.8 kg loaded

Magazine capacity: 20 or 30 rounds box (KE) and 6 rounds box (HE)

The history of the one of the most ambitious projects in the history of small arms, known as the OICW, or the Objective Individual Combat Weapon, began late in the 1986, when the US Army Infantry School at Ft. Benning published a military paper, named "Small Arms System 2000" (SAS-2000). Despite the current trends towards the caseless and fleschette ammunition and appropriate weapons, researched and developed under the ACR program (see HK G11 and Steyr ACR entries for some details), this paper stated that the conventional small arms already reached its technological peak, and the only way to increase the hit probability in the small arms is to introduce a weapon that will fire explosive and fragmentation warheads, combined with the smart fusing and sighting / aiming technologies. While the most small arms research during the late 1980s in the USA was conducted under the ACR program, the idea first developed in the SAS-2000 was supported by another US military paper, published in 1989 by the US Army TRADOC (Training & Doctrine) center. This paper, called "The Small Arms Master Plan" (SAMP), requested for a family of infantry "Objective" weapons, namely the Objective Individual Combat Weapon (OICW), Objective Personal Defense Weapon (OPDW), and the Objective Crew Served Weapon (OCSW). The SAMP stated that such weapons must utilize the latest developments in computers and visual technologies, as well as in the small arms, and combine both high explosive warheads and traditional bullets fire capabilities in a single weapon, that should be fielded circa 2000. Of cause, the timelines and most of the weight and cost requirements set in this paper looked unrealistic from the start, but the development of the Objective weapons began in the early 1990s.

During the early stages of research and development in the mid-1990 one out of the two teams was selected as a winner for further development contract. This team is lead by the US based Alliant Techsystems corporation (ATK), with the Heckler-Koch (Germany), Brashear and the Omega companies (both of USA) as the other team members. The ATK is responsible for system integration, and also develops the 20mm Air Burst munitions; HK is responsible for both the 5.56mm rifle and the 20mm grenade launcher; Brashear works on the sighting equipment and Omega provides the training means. The resulting weapon was type-classified by the US Army as the XM-29 circa 2002, and is scheduled to enter the service during the year 2008 in limited numbers. It will be then consequently upgraded with the new technologies then available. Present plans for fielding the M-29 are to issue four units per one infantry squad of 9 men. Early in the 2002 the XM-29 test weapons were successfully tested with the newest 20mm HEAB (High Explosive Air Bursting) munitions, which will be a major "kill factor" for the M-29 weapon. At the same time the "kinetic energy" part of the XM-29 was type-classified as the XM-8 light rifle, and, in the near future, could possibly replace the current Colt M4 carbines as a standalone compact conventional small arms.

XM29 status update (September 2005): following the increase of caliber of OICW grenade launcher component from 20 to 25mm, in 2004 it has been decided to split the OICW system into two separate weapons, the 5.56mm XM8 modular assault rifle (OICW Increment 1), and the 25mm XM25 airburst assault weapon / grenade launcher (OICW Increment 2). Development of the complete XM29 (OICW Increment 3) system has been shelved, and will be resumed in the future only if all current problems with OICW Block 1 rifle component are solved, and weight constraints of entire system are met.

XM-29 OICW Description.

The XM-29 is a combination weapon, which has the 20mm semi-automatic, magazine fed grenade launcher as its primary part, and the 5.56mm compact assault rifle as its secondary part. Both parts are assembled into the single one-man portable unit, with the addition of the target acquisition / fire control system (TA/FCS), which is an essential part of the whole system. The XM-29 will become an integral part of the future Land Warrior system, capable of communicating with the other parts of this system, including the tactical computers and helmet-mounted displays.

The grenade launcher is capable to fire in semi-automatic mode only, and is gas operated. It has a bullpup layout with the detachable box magazine located in the butt of the weapon. The rifled barrel is used to launch the 20mm grenades up to the 1000 meters range with good accuracy. In the standard configuration most of the fire controls for the grenade launcher part are located on the rifle part, including the single trigger for both firing modules. It is quite possible, however, that the separate stock will be developed for the grenade launcher part, so it will be possible to use it without the rifle part attached. The launcher has the provisions for the TA/FCS system to be mounted on its top, and the appropriate interfaces, so the data provided from the TA/FCS can be used to program the 20mm grenade fuses. These fuses, used for the 20mm HEAB ammunition, has multiple mode of detonation, including the direct impact mode and the Air Burst mode. In the latter mode the fuse is pre-programmed to explode the warhead at the preset range, which is calculated during the flight by counting the number of the grenade rotations. This allows do defeat targets without the direct impact, using the blast and fragmentation effect of the high explosive warhead. This is a major advantage over the present small arms, which in most cases require the direct hit on the target to be effective, as it allows for greater aiming errors, and also makes possible to defeat targets in defilade, like the trenches and so. The high explosive warhead also has the advantage of not being dependent on its velocity to be effective, so unlike with the bullets, its effectiveness does not decreased with the increase of range. The disadvantages of this system is the extreme complexity of the electronic fuses, which results in the high price of a single round of ammunition. The present plans stated that the one HEAB round must cost about US $25, and it is still to be seen which will be an actual price when the M29 system will be fielded. It is interesting that the present design of the HEAB ammunition actually has two small HE warheads at the front and at the rear of the projectile, with the electronic fuse module located between them. While the HEAB is considered a primary round for the 20mm grenade launcher, it is entirely possible do develop a low cost, direct hit only anti-armour 20mm round with Shaped Charge warhead, which will be effective against lightly armored vehicles (APC, MICV and alike) and various hardened targets.

The rifle, or "kinetic energy" part of the XM-29 system, on the other hand, is a fairy conventional, short-barreled assault rifle, derived from theHeckler-Koch G36 assault rifle. The basic "rifle" part of the XM-29 has no buttstock and no own sights, and thus can be used separately from the whole system only as emergency, personal defense weapon. While being mounted to the whole system, it can be used for a close quarters work, both defensive or offensive (the 20mm grenade launcher has it minimum range of fire of about 50-100 meters), or as an low-cost, low intensity medium range offensive weapon. Most of the XM-29 system controls are built into the "rifle" part, around the trigger guard.

The target acquisition / fire control system (TA/FCS) is the most expensive and complicated unit of the whole system, since it must combine day and night vision capabilities, laser rangefinding unit, ballistic computer and various interfaces to the grenade launcher and external systems. It is used to find the targets in any light and weather conditions, determine the range to the target, calculate and display the aiming data, so the grenade or bullet could be fired to the desired point of impact, and then supply the data to the grenade launcher, so the range could be preset into the grenade fuse. In the case of damage to the TA/FCS the 20mm grenade launcher still can be used in the direct impact mode, as well as the rifle part of the system.

The current research and testing showed that the XM-29 can be up to 500% more effective than the present small arms, but it is still to be seen if all the requirements will be met in the resulting system, especially regarding to the reliability of electronic components, weight, and, at last but not at least, the unit price.

XM8 Lightweight Assault Rifle (USA)

XM8 rifle in basic infantry configuration, as displayed in January, 2004, at the ShotShow-04 in USA

XM8 rifle in "automatic rifle" (light machine gun) configuration. Notelonger barrel and folded bipods under the forearm

XM8 rifle in "sharpshooter" (parasniper) configuration. While sightlooks similar to red-dot, mounted on other variants, it is of 3.5X magnification; spare magazine is clamped to the right side of the magazine inserted into the rifle.

XM8 rifle in Compact (SMG / PDW) configuration, with shortened barrel.

Author of this website is posing with XM8 at the ShotShow-2004, Las Vegas,USA.

Caliber: 5.56x45 mm NATO

Action: Gas operated, rotating bolt

Overall length: 838 mm in basic configuration, butt extended

Barrel length: 318 mm in basic configuration; also 229 mm in Compact and508 mm in Sharpshooter and SAW versions

Weight: 2.659 kg empty in basic configuration

Rate of fire: ~ 750 rounds per minute

Magazine capacity: 30 rounds (STANAG) or 100-rounds double drum inAutomatic Rifle/SAW role

The development of the XM8Lightweight Assault Rifle was initiated by US Army in the 2002, when contractwas issued to the Alliant Techsystems Co of USA to study possibilities ofdevelopment of kinetic energy part of the XM29 OICW weapon into separate lightweight assault rifle, which could, in the case of success,replace the aging M16A2 rifles and M4A1 carbines in US military service. XM8 is being developed by the Heckler-Koch USA,a subsidiary of famous German Heckler-Koch company. According to the present plans, the XM8 should enter full production circa 2005, if not earlier, several years before the XM29OICW. The XM8 (M8 after its official adoption) should become a standard next generation US forces assault rifle. It will fire all standard 5.56mm NATO ammunition, and, to further decrease the load on the future infantrymen, a new type of 5.56mm ammunition is now being developed. This new ammunition will have composite cases, with brass bases and polymer walls, which will reduce weight of the complete ammunition, while maintaining compatibility with all 5.56mm NATOweapons. Along with 20% weight reduction in the XM8 (compared to the current issue M4A1 carbine), this will be a welcome move for any infantryman, already overloaded by protective, communications and other battle equipment.

The XM8 will be almost similar to the "KE" (kineticenergy) part of the XM29 OICW system, being different mostly in having a telescoped plastic buttstock of adjustable length, and a detachable carrying handle with the sight rail.

As of mid-2004, XM8 now is undergoing wide-scale testing in several units of US Army, and is receiving a positive feedback.

XM8 status update (September 2005): Following several complains about non-competitive procurement of the XM8 system from Heckler-Koch USA, US Army first opened the bidding for contract to other companies, and then, in the July 2005, suddenly suspended the entire OICW Increment 1 program to re-think the entire set of requirements for the possible replacement of current M16 rifles and M4 carbines. These requirements will be re-viewed as Joint Services effort. At the present time, it seems that development of HK XM8 is suspended; it may be resumed if XM8 suit the new US Joint Service Requirementsfor a new assault rifle system; or, it may not. We will watch this process closely and update this article when new information will be available.

Technical description.

The XM8 is a derivative of the Heckler-Koch G36 assault rifle, and thus it is almost similar to that rifle in design and functioning.XM8 features a short piston stroke, gas operated action, with rotating bolt locking. Barrels are quick detachable, and planned to be available in several sizes, ranging from 229 mm (9.5 inch) for Compact/PDW version, 318mm (12.5 inch)in Basic version, and two 508mm (20in) barrels, one for Sharpshooter/Sniper version, and heavier one (along with bipod) for Squad Automatic Rifle role. The entire construction is modular and built around the polymer receiver with boltgroup; Magazine housings could be easily swapped for compatibility with various types of magazines; various buttstocks could be installed in a second for various roles (standard buttstock is a telescoped 5 position adjustable one).Top of the receiver is fitted with proprietary sight rail, which can accept illuminated red-dot (collimator) sight, or any other type of sighting equipment.Detachable forend will be available in various sizes, and could be replaced withXM320 40mm grenade launcher (the improved HK AG36).

Ambidextrous fire controls are mounted on the trigger unit, integral with pistol grip and triggerguard, and in basic configuration are planned to deliver single shots and full auto fire.The G36-type ambidextrous charging handle is located at the top of the receiver, below the removable carrying handle.

SIG 516 tactical rifle (USA)

SIG 516 Patrol rifle

SIG 516 Precision Marksman rifle

The family of SIG 516 Tactical rifles is a most recent product of the US-based branch of the international arms maker SIG-Sauer . Intended primarily for the US markets, this family of weapons included two basic semi-automatic versions, intended for civilian and Law Enforcement markets. The same family also includes selective-fired "assault rifles", strictly intended for Government (LE and Military) use. The SIG 516 Tactical rifles are closely patterned after the Ar-15 / M16 family of rifles, but with certain improvements, such as piston-operated gas action with adjustable gas regulator. It is possible that select-fire version of the SIG 516 rifle will also compete for replacement of the current US Army's M4 carbine.

The SIG 516 Tactical rifles are gas operated weapons that use Ar-15 / M16 configuration, with aluminum alloy upper and lower receivers assembled by two captive cross-pins. The basic Ar-15 / M16-style rotary bolt gas operated action is improved with addition of the short-stroke gas piston that runs inside handguards, above the barrel. The gas block is equipped with manually adjustable gas regulator. The trigger unit, manual safety and feed system (magazines, bolt release etc) are also similar to the Ar-15 / M16. The SIG 516 Patrol rifles feature shorter 16 inch barrels and adjustable M4-type buttstocks. The SIG 516 Precision Marksman rifles have longer 18-inch barrels and adjustable 'sniper' stock. In either version, barrels are chrome-lined. The sighting equipments is installed using integral Picatinny rail on the top of the receiver and on the additional 4 rails on the forend.

SIG 716 tactical rifle (USA)

SIG 716 Patrol rifle with EOTech red-dot and back-up iron sights, as displayed at ShotShow 2010

The family of SIG 716 Tactical rifles is a most recent product of the US-based branch of the international arms maker SIG-Sauer. This family reflects current resurrection of the interest toward 7.62mm NATO / .308 Win weapons among US and other NATO troops, currently operating in Afghanistan and Iraq. It also targets to US domestic LE and civilian markets, as the SIG 716 family of rifles includes both Selective-fire (LE/Military only) and Semi-automatic (Civilian legal) guns. The SIG 716 Tactical rifles are closely patterned after the Ar-15 / M16 family of rifles, but are somehow bigger due to the bigger and more powerful caliber, and with certain improvements, such as piston-operated gas action with adjustable gas regulator. The SIG 716 Tactical rifles can be considered to be bigger brothers to the very similar family of SIG 516 tactical rifles, which are chambered for 5.56mm / .223 caliber ammunition. Obviously, it also will compete against such 7.62mm rifles as HK 417, FN SCAR/H Mk.17 and a variety of other 7.62mm Ar-15 / M16 knock-offs. The rifles shown here are prottypes, and it is believed that production rifles will begin to appear on US market not earlier than 2011.

The SIG 716 Tactical rifles are gas operated weapons that use Ar-15 / M16 configuration, with aluminum alloy upper and lower receivers assembled by two captive cross-pins. The basic Ar-15 / M16-style rotary bolt gas operated action is enlarged and strengthened to work with more powerful 7.62mm / .308 caliber ammo and improved with addition of the short-stroke gas piston that runs inside handguards, above the barrel. The gas block is equipped with manually adjustable gas regulator. The trigger unit, manual safety and feed system (magazines, bolt release etc) are also similar to the Ar-15 / M16. The SIG 716 Patrol rifles feature shorter 16 inch barrels and adjustable M4-type buttstocks. The SIG 516 Precision Sniper rifles have longer 20-inch heavy profile barrels and adjustable 'sniper' stock. In either version, barrels are chrome-lined. The sighting equipments is installed using integral Picatinny rail on the top of the receiver and on the additional 4 rails on the forend.

Military / LE only selective fire versions feature full-automatic and/or 3-round burst firing modes, civilian SIG 716 rifles will fire only in semi-automatic mode. SIG 716 rifles are compatible with current Armalite AR-10 Gen.2 magazines, which are available in 10- or 20-round capacities.

FN SCAR: Mark 16 and Mark 17- Special Forces Combat Assault Rifle (USA/ Belgium)

FN SCAR-L / Mk.16 rifle prototype (1s generation, late 2004), left side view

FN SCAR-L / Mk.16rifle, 2nd generation prototype, with FN EGLM 40mm grenade launcher attached

FN SCAR-H / Mk.17 rifle prototype in CQC (Close Quarter Combat,short barrel) configuration,7.62x51 mm NATO version

FN SCAR-L / Mk.16 rifle partially disassembled; note additional quick-detachable barrel

Image: Christopher Rohling via CharlesCutshaw

5.56mm NATO FN SCAR-L / Mk.16 rifles of current (2007/2008) production, top to bottom in Long Barrel (LB), standard (Std) and Close Quarter Combat(CQC) configurations

Image: FNH USA

7.62mm NATO FN SCAR-H / Mk.17 rifles of current (2007/2008) production, top to bottom in Long Barrel (LB), standard (Std) and Close Quarter Combat(CQC) configurations

Image: FNH USA

The US Special Operations Command(US SOCOM) issued a solicitation for the procurement of SOF CombatAssault Rifles (SCAR)on October 15th, 2003. This solicitation requested a new combat rifle,specially tailored for the current and proposed future needs of the US Special Forces,which are somewhat different from latest generic US Army requirements,which are being fulfilled by the newest Heckler-KochXM8 assault rifle. The key difference in basic requirements between XM8 and SCAR is that, while XM8 is a single-caliber weapon system, tailored for 5.56x45mm NATO ammunition, the SCAR should be available in various different calibers.Initial SOF requirements included two basic versions of SCAR system - the SCAR Light (SCAR-L), available in 5.56mm NATO, and the SCAR Heavy (SCAR-H), which should be initially available in significantly more powerful 7.62x51 NATO chambering, and should be easily adaptable in the field to other chamberings. These other chamberings initially include the well-spread 7.62x39 M43 ammunition of the Soviet / Russian origins, and probably some others (like the proposed 6.8x43 Remington SPC cartridge, especially developed for US Special Forces).The keyidea of SCAR rifle system is that it will provide the Special Forces operators with wide variety of options, from short-barreled 5.56mm SCAR-L CQC variation,tailored for urban close combat, and up to long range 7.62x51 SCAR-HSnipervariant, as well as 7.62x39 SCAR-H, which will accept "battlefield pickup" AK-47/AKM magazines with 7.62 M43 ammunition, available during the operations behind the enemy lines. Both SCAR-L and SCAR-H shall be initially available in three versions, Standard(S), Close Quarters Combat (CQC) and Sniper Variant(SV; now it is dubbed Long Barrel - LB). All these variants, regardless the caliber and exact configuration, will provide the operator with the same controls layout, same handling and maintenance procedures, and same optional equipment, such as sights,scopes, and other current and future attachments.

Late in 2004 USSOCOM announced, that the winner for the initial SCAR contracts is the FN USA, an US-based subsidiary of the famous Belgian company Fabrique Nationale Herstal. prototype rifles were manufactured by FN Manufacturing Inc, US-based subsidiary to FN Herstal; This company will also handle series production of rifles. Starting mid-2005, first SCAR rifles went to end users in US Special Operation Forces. Since USSOCOM uses Navy-type "mark" designations, SCAR rifles were officially designated as 5.56mm Rifle Mark 16 (SCAR-L / Light) and 7.62mm Rifle Mark 17 (SCAR-H/ Heavy).It is believed that Mk.16 and Mk.17 rifles will gradually replace most rifle systems now in service with US SOCOM forces, such as M4 carbines, M16 rifles, M14 rifles and Mk. 25 sniper rifles.

As it turned out, FNSCAR rifles are not based on any previous weapons but designed from the scratch. In all variants FN SCAR rifles feature gas operated, short stroke piston action with rotating bolt locking. Bolt system appears to be somewhat similar to that of FNMinimi / M249 SAW machine gun. This system apparently is less sensitive to fine sand, dust and any other fouling inside the receiver, than any system withM16-type multi-lug bolt and plunger-type ejector.

Receiver is made from two parts, upper and lower, connected with two cross-pins. Upper part is made from extruded aluminium, lower part is made from polymer. SCAR-L and SCAR-H use similar upper receivers that differ only in the size of ejection port. Other different parts include caliber-specific bolt, barrel, and lower receiver with integral magazine housing. Parts commonality between SCAR-L and SCAR-H is astonishing 90%. Barrels are quick-detachable, and held in the upper receiver with two cross-bolts. Barrel change procedure requires minimum amount of tools, takes just several minutes and there is no need to adjust the headspace after the change.

The trigger unit with ambidextrous safety-fire mode selectors witch allows for single shots and full automatic fire, with no provisions for limited-length bursts mode. The charging handle could be easily installed on either side of the weapon, so the upper receiver has respective cuts on both sides. Top of the upper receiver is covered by the full-length integral Picatinny rail (MIL-STD 1913); additional Picatinny rails are mounted on both sides and under the free-floating handguards. Side-folding polymer buttstock is adjustable for length of pull, and is shaped to provide positive cheekrest with adjustable cheek support. SCAR rifles are fitted with removable, adjustable iron sights, with folding diopter-type rear sight on the receiver rail, and folding frontsight onthe gas block. Any additional type of sighting equipment, necessary for current tasks, including telescope and night sights, can be installed using MIL-STD 1913 compatible mounts.

Mk.16 SCAR-L rifle will use improved M16-type magazines, made of steel; Mk.17 SCAR-H will use proprietary 20-round magazines in 7.62x51 NATO chambering, or standard AK-type magazines in proposed 7.62x39 M43 chambering. Current prototypes of SCAR rifles do not have bayonet mounts,and, probably, will never have one.

Special thanks to Charles Cutshawfor invaluable information and images

Robinson Armaments M-96 and XCR rifle (USA)

Robinson Armaments M-96 rifle in standard configuration

Robinson Armaments M-96 rifle in top-feed ("Bren-type") configuration,with short barrel

Robinson Armaments M-96 RAV-02 assault rifle (selective-fired), version chambered for 7.62x39mm

Robinson Armaments XCR rifle, caliber 5.56x45mm, with open sights (detachable and folding).

Robinson Armaments XCR rifle, caliber 5.56x45mm

Robinson Armaments XCR rifle, caliber 6.8x43mm Remington SPC, with Trijicon ACOGtelescope sight

Data for RobArm XCR rifle

Caliber: 5.56x45mm NATO; also 6.8x43mm Remington SPC and 7.62x39 M43

Action: Gas operated, rotating bolt

Overall length: 959 mm (stock open), 696 mm (stock folded)

Barrel length: 407 mm (other lengths available)

Weight: 3.4 kg

Rate of fire: n/a

Magazine capacity: 30 rounds

American company Robinson Armament Cointroduced its M-96 Expeditionary Rifle in late 1990s. It was basically a semi-automatic only modular weapon, patterned after famous Stoner 63 weapon system. It was available in several configurations; in about 2002,Robinson Armament also introduced a military / police only RAV-02 rifle, which was based on same design but added selective-fie capability. Over that time,M-96 series rifles were no more than limited production items, sold mostly on civilian US market. Unlike original Stoner 63 design,no belt-fed versions were made in M-96 line.

In about 2004, Robinson Armament unveiled a new design, which, while retainingbasic modular concept, stepped out of Stoner pattern in several aspects. The new XCR rifle was submitted to SCAR special forces rifle trials, which were won by FNMk.16 and Mk.17 SCAR rifles. Since mid-2006, RobArm XCR rifles are sold on civilian US market in semi-automatic only versions; selective-fired versions are available only for government buyers.

RobArm M-96 rifles were built on single,universal receiver, made from stamped steel. These receivers hosted quick-detachable barrels and basic gas-operated actions with long-stroke gas piston and rotary bolt locking. Receivers had mounting points for trigger units on "top" and "bottom" surfaces, and feed unit mounting points on "bottom" side only. In standard rifle configuration receiver is put with gas tube below the barrel, and magazine and trigger units mounted on the underside of weapon. In the "Bren-type" configuration, receiver is turned upside down so gas tube lies above the barrel, and magazine inserts from the top; the trigger unit is installed on the opposite, "bottom" side of weapon. Both trigger unit and magazine feed units also were made from stamped steel. Barrels with appropriate front sight mounts were used for every configuration, and rear sight block was attached to the mounting points on receiver, opposite to trigger unit. Guns were fitted with detachable, solid polymer stocks, and detachable plastic forends / handguards. In"standard" rifle and carbine configurations, charging handle was located at the left side of receiver, and ejection was to the right. In the"Bren-type" configurations, charging handle was on the right, and ejection was to the right (because the receiver was turned "upside down").

RobArm XCR rifle is quite different from M-96. Most important, it abandoned the idea of single receiver with detachable units, that can be turned upside-down. XCR rifle reverted to the more common upper / lower receiver configuration, in which upper receiver hosts removable barrel, gas system, andbasic action with rotary bolt locking. Gas system features traditional gas piston, and four-position gas regulator. Bolt has three locking lugs and locks into the barrel extension. Lower receiver hosts trigger unit and pistol grip,and has an integral magazine housing. Manual safety (which doubles as fire mode selector in "military" versions) is located on lower receiver, above the pistol grip, and can be located on left side only or both sides of receiver.Bolt catch release button is located at the rear of magazine veil, just ahead of trigger guard. Cocking handle is located at the left side of upper receiver, and can be used to assist the bolt closure.

XCR rifles are fitted with side-folding skeleton buttstock. Top of receiver is shaped into integral Picatinny type accessory rail, with three additional rails located around the barrel at 3, 6, and 9 o'clock positions. For more convenient use, these rails can be covered with special polymer panels, that form rifle's forend / handguard. There are no standard sighting equipment "as is",but any compatible open or telescopic and night sights can be installed using Picatinny rail.

Z-M Weapons LR-300 assault rifle / Para USA Tactical TargetRifle (USA)

Z-M Weapons LR-300-ML assault rifle, early (circa 2001) version

Z-M Weapons LR-300-SR semi-automatic rifle, late production version(circa 2006)

Para USA Tactical Target Rifle, with buttstock open

Para USA Tactical Target Rifle, with buttstock collapsed

Specifications forZ-M Weapons LR-300 rifles

Specificationsfor Para USA Tactical Target Rifle

The LR-300 rifle was manufactured by the small US-based company Z-M Weapons between 2000 and 2007, when all rights for the design were sold to the Para USA, the US-based subsidiary of the Canadian pistol maker Para-Ordnance Ltd. The reworked LR-300 rifle will be sold in USA as Para Tactical Target Rifle, with first sales sheduled to "early 2009".

Original LR-300 (LR stands for Long Range) rifles were designed by Alan Zitta as an upgrade to the well known and popular M16 / AR-15 rifle. In fact, LR-300 and Para TTR both use standard AR-15-typelower receivers; only upper receivers are different and contain patented modified gas system. The key reason for tha modification was to prowide AR-15-type weapon with capability to mount side-folding stock rather than partially collapsible M4 carbine-typestock. Z-M Weapons intended its rifles mostly for military and law enforcement personnel, by offering LR-300-ML weapons with short barrels and select-fire capability. Civilian (semi-automatic only) versions also were offered to general public, but at prices well above the average price of AR-15-type rifle. Itis not known yet if the new Para Tactical Target Rifles will also be offfered in military (select-fire) version or not; current Para USA advertising suggests that only semi-automatic weapons (and upper receiver conversion kits) will be offred, at least initially.

TheLR-300 rifle is gas operated, and utilizes modified Stoner-type direct gas imingement system. In this modified system, the gas key is extended forward to form the tube, that protrudes forward from the receiver and into the handguard. The protruding part of the gas key tube is used to host the bolt return spring, which is placed between the front receiverwall and the collar at the front of the gas key tube. The gas tube,which runs rearward from the gas block / front sight base, is strengthened as its rear end floats freely to enter the extended gaskey tube when bolt group is in the battery. That way, at least some of the hot gases from inside the gas carrier are expelled outside the receiver and into the inner handguard area, through the extended gaskey tube, once it has left the gas tube during the bolt group recoilmovement. Additional benefit of this system is that it allows the boltcarrier to be made twice as short compared to the standard AR-15- type bolt carrier. In turn, this results in the fact that there's no need for the recoil buffer tube, which is normally protruding backward from the AR-15-type lower receiver. Because ofthis feature, most LR-300 rifles are fitted with side-folding shoulder stocks, either sceletonized non-adjustableones made from metal or polymer ones, adjustable for length of pull. Otherwise the LR-300 is similar to the AR-15-type weapons and has similar trigger / safety arrangements, magazine housing and bolt stop device.