.303 inch Tracer G Mark IV to G Mark 8 & PG Mark I
Tracer G Mark IV
In 1939 Bomber Command requested an air to air tracer with a range of 400 yards (later increased to 600 yards) to act as an aid to range estimation by air gunners.Development work was carried out by Kynoch and the new tracer was introduced in 1940 for Air service
"Cartridge S.A. Tracer .303 inch G Mark IV" and "IVz"were approved to design DD/L/10847 in May 1940 for Air service and shown in Lists of Changes Paragraph B.5100 dated August 1941. Later when use was extended to Naval service designs NOD 4855 and NOD 4856 applied.
.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "G IV" or "G IVZ". Canadian "universal" cases had a purple primer annulus and a white bullet tip.
The early production bullets had an envelope of cupro-nickel with a front core of lead/antimony. Behind this was the short copper or gilding metal tracer canister containing 4.5 grains of SR390 tracing composition and 6 grains of SR370 priming composition which was closed by a brass washer. The bullet was an air/day tracer and traced to 550 yards at 10,000 feet. The short bullet weighed 158 grains and was 1.35" (34.2mm) long.
Later to simplify production, the longer envelope and tracer canister of the G Mark V bullet was used with an inert filler at the front of the canister to maintain the trace at 550 yards. This bullet was 1.46" (37mm) long and weighed 151 grains. It was known as the G Mark IV/2 but was later redesignated G Mark VI. (see below)
Both the G Mark IV and IV/2 had white bullet tips but British made examples often had the tip colour omitted.
The propellant charge was 36 grains of Cordite MDT 5-2 with one wad or 35 grains of nitro-cellulose to give a velocity of about 2,360 fps at a pressure of 19 to 20 tsi.
Tracer G Mark V
The tracer G Mark V was the Naval night equivalent of the RAF G Mark IV air to air day tracer.
"Cartridge S.A. Tracer .303 inch G Mark V" and "Vz"were approved to design DD/L/11817 in June 1942 for Naval service and shown in Lists of Changes Paragraph B.8392 dated September 1943. The design was later replaced by NOD 5956 and NOD 6322.
.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "G V" or "G VZ".
The bullet had an envelope of cupro-nickel or gilding metal clad steel with a front core of lead. Behind this was the copper or gilding metal tracer canister containing 20 grains of N.T.3 tracing composition and 2 grains of P.6 priming composition which was closed by a brass washer. The bullet was an air/night tracer and traced dark to 50 yards and then to 550 yards at 10,000 feet. The bullet weighed 161 grains and had a grey tip for identification. The shade of grey varies fro off-white to dark grey.
The propellant charge was 36.5 grains of Cordite MDT 5-2 with one wad or 38 grains of nitro-cellulose to give a velocity of about 2,300 fps.
Tracer G Mark VI
As discussed above, the tracer G Mark VI was the retitled G Mark IV/2 air to air day tracer.
"Cartridge S.A. Tracer .303 inch G Mark VI" and "VIz"were approved to design NOD 6322 in October 1942 for Naval service and shown in Lists of Changes Paragraph C.555 dated March 1945.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "G VI" or "G VIZ". ("G 6" or "G 6Z" after 1944)
The bullet had an envelope of cupro-nickel, cupro-nickel clad steel or gilding metal with a front core of lead/antimony. Behind this was the copper or gilding metal tracer canister, the front portion of which was filled with bakelite or paper. Behind this was 5 grains of SR 390 tracing composition and 6 grains of SR 370 priming composition which was closed by a brass washer. The bullet was an air/day tracer and traced to 550 yards at 10,000 feet. The bullet weighed 151 grains and had a white tip for identification.
The propellant charge was 35 grains of Cordite MDT 5-2 with one wad or 36 grains of nitro-cellulose to give a velocity of about 2,300 fps at a pressure of between 19 and 20 tsi.
Tracer G Mark VII
A new Naval tracer was introduced in 1944.
"Cartridge S.A. Tracer .303 inch G Mark VII" was approved to design NOD 6322 in October 1944 for Naval service and shown in Lists of Changes Paragraph C.554 dated March 1945.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "G 7" although it is possible early production used the code "G VII".
The bullet had an envelope of gilding metal clad steel with a front core of lead/antimony. Behind this was the copper or gilding metal tracer canister containing 12 grains of SR 368A tracing composition and 2 grains of SR 462 or 462G priming composition, closed by a brass washer. The bullet was a dark ignition tracer that traced dark to 100 yards and then bright to 1,000 yards. The bullet weighed 151 grains.
The propellant charge was 35 grains of Cordite MDT 5-2 with one wad or 36 grains of nitro-cellulose to give a velocity of about 2,300 fps at a pressure of between 19 and 20 tsi.
Tracer G Mark 8
In 1943 the Navy reported problems with tracers fired at extremely low temperatures and requested a heavier tracer with a degraded ogive to better match other types as the bullet became lighter.
Trials were held in 1944 with a variety of tracer bullets including a round nosed Ball Mark VI type but eventually one with a degraded ogive was recommended for immediate adoption.
"Cartridge S.A. Tracer .303 inch G Mark 8" was approved to design NOD 6322 in June 1945 for land and Naval service and shown in Lists of Changes Paragraph C.1909 dated December 1945. The design was later changed to DD/L/14006.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "G 8".
The bullet was unlike all previous marks of tracer and had a blunter ogive of 3.5 CRH. The envelope was cupro-nickel or gilding metal with a front core of lead/antimony. Behind this was the copper or gilding metal tracer canister containing 12 grains of SR 368A tracing composition and 2 grains of SR 462 or 462G priming composition, closed by a brass washer. The bullet was a dark ignition tracer that traced dim to 100 yards and then bright to 1,000 yards. The bullet weighed 169 grains.
The propellant charge was 36.5 grains of Cordite MDT 5-2 to give a velocity of about 2,370 fps at a pressure of between 19 and 20 tsi.
Tracer PG Mark I
The final type of tracer approved was the little used Practice Tracer PG Mark I.
"Cartridge S.A. Practice Tracer .303 inch PG Mark 1" and "1z" were approved to design DD/L/14006 in January 1945 and shown in Lists of Changes Paragraph C.1829 dated December 1945.
The case was a normal Berdan primed service case with a red primer annulus and included the headstamp code "PG1 " or "PG1Z". It had a dark blue band around the case above the rim.
The bullet was a standard G Mark II bullet with the normal components and weighed 154 grains. A CIA (A) document however shows the bullet to weigh 136 grains but it is not known if this lighter bullet ever went into production. It is unlikely given that the PG Mark 1 was only made for a short time in 1945.
The propellant charge was 19.5 grains of Cordite MDT 5-2 or 20 grains of nitro-cellulose to give a velocity of about 1,250 fpsi.