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One of the many lessons learned during the Second Boer War in South Africa was that the .303 inch cartridge was lacking in terms of velocity and accuracy compared to the 7x57mm Mauser round used by some of hte Boers.
The .303 inch Short Magazine Lee Enfield had been adopted in 1903 but was not received well, being considered to be inherently less accurate than the earlier long Lee Enfield. The War Office also saw it as an interim solution until a new rifle and higher velocity cartridge could be developed.
Accordingly the Chief Superintendant of Ordnance factories had in 1908 requested the Director of Artillery to test a new design of .256 inch ammunition. This was extended in 1909 to include .276 inch ammunition. Meanwhile the Small Arms Committee issued a draft specification in September 1910 for a new infantry rifle which was to eventually become the Pattern 1913 rifle.
.256 inch
Initial research was intended to produce a .256 inch crtridge with a 150 grain bullet at a muzzle velocity of 2,800 feet per second. Nine different case types were designed with bullets varying in weight between 144 and 155 grains.
Bullets generally had lead cores with cupro-nickel envelopes but some steel core designs were tested with copper envelopes.It was calculated that to produce the desired 2,800 feet per second a charge of 48-50 grains of Cordite MDS would be required which in turn meant a cartridge with an unaccaeptable length. This was one of the principal reasons that efforts were concentrated on the .276 inch designs.Despite this, work appears to have continued in some part on .256 inch designs into 1911-13.Left: two different .256 inch case designs, believed to be variants of design RL 16007.
Two case drawings of .256 inch experimental rounds, (Left) RL16007 and (right) RL17303. Note the "Continental" Berdan primer on RL16007 with a single fire hole through the anvil.
.276 inch
Between 1909 and 1914 a prodigious amount of work was carried out on experimental .276 inch ammunition. There were some 30 different case types and fifty four bullet types designed giving at least 48 different cartrdiges. In addition some design numbers covered both case and bullet.
Most were only made in very limited numbers and have only survived in the form of drawings. It is impractical to show them all here but
some example drawings are illustrated.Since Woolwich were developing the ammunition and RSAF Enfield the rifle, some designs were made as solid steel dummies for use in rifle development. Two solid steel .276 inch dummy rounds, (left) possibly RL 16938 and (right) unknown.Throughout the trials problems had been experienced with severe barrel fouling and tests were carried out using bullets with envelopes of different alloys of cupro-nickel and with steel envelopes. Further trials were held in August 1912 with bullets with "German bullet envelope material", which was cupro-nickel clad steel. These rounds were loaded with nitrocellulose propellant and this appears to be the first time that this had been utilised instead of Cordite.Finally, case design RL18000 emerged as the likely final choice with various bullets of 165, 175 and 188 grains. The Small Arms Committee decided all were generally acceptable, but preferred the 165 grain design as the trajectory was flatter to 800 yards than the 175 grain. They recommended that one thousand rifles should be made up for troop trials.The cartridge actually issued for the troop trials was RL18000C which apart from the weight of the bullet differed only in minor case details from the earlier RL18000A.
The troop trial cartridge to design RL 18000C had a case with slightly thinner case walls to increase powder capacity and an annular groove around the primer to prevent "caps out". Case capacity was .247 cubic inches.The bullet weighed 165 grains and had a 98/2% lead/antimony core with a cupro-nickel clad steel envelope. It was secured in the case by six neck indents.The propellant charge was 49.3 grains of Cordite MDT to give an estimated muzzle velocity of about 2,700 feet per secon, but oddly actual velocity and pressure are not documented in surviving records.The great majority of troop trial ammunition was manufactured by the Royal Laboratory with the headstamp simply "R /|\ L", but it was also made by Kings Norton, Kynoch and Greenwood and Batley. Although the troop trial round was never formally approved, it was referred to as "Cartridge S.A. Ball .276 inch Mark I" in some documents and on packet labels. Indeed, the headstamp of both the Kynoch and Kings Norton made rounds included the numeral "I".Left ; Troop Trial ball round RL 18000CRight: Packet label of same.
Heavy metal fouling in the bore remained a problem and attempts continued to overcome this.Although impossible to identify externally, some Kings Norton production headstamped "KN 13 I" had bullets with the bearing surface wrapped in steel wire.The troop trial results were returned in August 1913 and whilst the reports were generally favourable about the rifle, the ammunition was still far from satisfactory.Reports were received of high pressure causing caps to blow out and difficult extraction. Finally a rifle burst at Aldershot when a cartridge "cooked off" in a hot chamber.
Work continued into 1914 on both propellant and the metal fouling problem but the outbreak of war in August 1914 brought work to a close.
Winchester Made .276 inch Ball
In August 1916 Winchester Repeating Arms made a batch of .276 inch rounds, apparently to the normal RL18000C design. It is known that this contract was placed by the Canadian authorities but the reason is unknown.
The rounds are headstamped "WRA Co. 8-16"
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