7.62mm NATO Drill & Inspection
7.62mm Drill
Prior to the formal introduction of the L1A1 drill round a number of improvised drill rounds were made using converted ball rounds.
RSAF Enfield used drill rounds converted from FN made ball rounds with the headstamp "FN 54 (+)". These had three holes drilled in the case and an empty cap chamber. Incidentally, these are the earliest British or Belgian rounds to include the NATO symbol.
British RG made ball rounds were converted to drill by adding holes to the case and a wood spacer to support the bullet. The empty cap chamber was stained red.
The headstamp was "RG 54 7.62 A1"
Drill L1A1
"Round 7.62mm Drill L1A1" was approved to design D6/L/1331/G/108 in march 1954 and shown in Lists of Changes Paragraph C.6326 dated November 1954.
It had a chromed brass case and an empty cap red painted chamber that retained the anvil but omitted the fire holes. There were three vertical flutes in the case painted red. The headstamp included "A1".
The bullet was a special flat based bullet weighing 150 grains (9.72 grams) with a gilding metal jacket and a lead alloy core.
The L1A1 proved to be unsatisfactory as the flutes resulted in cross feeding in weapons and the round was found to be insufficiently strong with bullets working loose.
In 1955 a series of trials were held with four types of drill round.
"Type A" This had flutes as in the L1A1 with normal case mouth hardness and a double neck cannelure. The headstamp is not known.
"Type B" This had an unplated case with shallow flutes and increased mouth hardness from 125 to 140 DPN. Identification was by blue painted flutes and cap chamber. The headstamp was "RG 55 7.62".
"Type C" This has an unplated case but length to shoulder was low. It had a double neck cannelure and identification was by white painted flutes and cap chamber. The headstamp was "RG 55 7.62".
"Type D" This had an unplated case with shallow flutes and a single mouth cannelure. Mouth hardness was 95 +- 15 DPN and identification was by red painted flutes and cap chamber. The headstamp was that of the L1A1 drill round, "RG54 7.62 A1"
Above. Type B drill, label for same, Type C drill.
Type C was judged to be the best round as it was found that shallow flutes and increased mouth hardness solved the problems encountered with the L1A1. In 1956 modified drill rounds of this pattern were sent to the School of Infantry at Hythe for eight weeks of testing. These rounds were unheadstamped. the rounds were found to be satisfactory so were approved as the L1A2.
Drill L1A2
"Round 7.62mm Drill L1A2" was approved to design S1/1279/G/1304 in June 1956.
The brass case was chrome plated and originally had an empty red painted cap chamber without anvil or fire holes. Later approval was given to retain these. The case had three shallow red painted flutes and the headstamp usually included "L1A2".
The bullet had a lead alloy core and a long GMCS envelope left open at the rear to fit over the wood distance piece. There was a double neck cannelure.
In 1977 efforts were made to produce a cheaper and hopefully more durable round. These trials included using various plastics instead of wood for the support piece. Despite the recommendation that these be approved for service, the rounds made to the modified specification continued to use wooden distance pieces.
"Round 7.62mm Drill L1A2 Reduced Standard" was approved in about 1977.
It had a chrome plated brass case without fire holes or cap, but with the anvil present. There were three flutes in the case, deeper than those of the L1A2 round and neither the flutes nor the cap chamber were painted red. The headstamp did not include the cartridge designation and used the then standard generic three position "universal" headstamp, typically "RG 82 (+)".
The bullet had a lead alloy core and a long GMCS envelope left open at the rear to fit over the wood distance piece and was secured by a simple neck crimp. In addition to wood, various plastics were approved for the distance piece.
Non standard drill rounds
In addition to the above, Radway Green also manufactured various non standard drill rounds, usually from ball components.
Those that were chromed were often made for display purposes at exhibitions and were not for general issue. Others that were left plain and without caps were made for packaging trials to test the suitability of different packages for air drop. Sometimes these were marked with a green bullet tip and some were weighted with small lead shot.
7.62mm Inspection
Shortly after the 7.62mm round had been adopted in 1953 there arose a need for an inspection round for factory use, before any formal inspection round had been approved.
These were locally made at RSAF Enfield and consisted of a service ball case with a snapped cap and one hole bored in the case. The headstamp was "RG 55 7.62 A1".
The bullet was a service ball bullet secured in the case by a steel pin passing through the neck of the case and bullet. The bullet was originally lacquered green but this soon wore off.
Inspection L3A1
" Round 7.62mm Inspection L3A1" was approved to design S1/12652/G/1360 in January 1955 and shown in Lists of Changes Paragraph C.6742 dated August 1955.
The case was of normal external form initially with a blind primer pocket although later versions from the 1980s have both anvil and fire holes. The case was chromed, usually but not always with a matt finish and has no flutes. As an economy measure some rounds were manufactured in the 1960s with plain brass cases.,
Until the 1980s the headstamp included "L3A1" but later rounds use the then standard universal headstamp with no cartridge nomenclature included.
The bullet had a lead alloy core and a long GMCS envelope left open at the rear to fit over the wood distance piece and was secured by a double neck crimp. In addition to wood, various plastics were approved for the distance piece.
Inspection L41A1
"Round 7.62mm Inspection L41A1" is specially made for the inspection and adjustment of the 7.62mm Chain gun fitted to certain British armoured vehicles. It is manufactured by SDE in the UK.
It consists of a one piece hollow brass cartridge, heavily chrome plated with two circumferential grooves mid way in the case for additional identification.
Inspection L42A1
This round is something of a hybrid. Although given a nomenclature of "7.62mm Bisley Inspection" and manufactured by Radway Green, this round was made for the National Rifle Association at Bisley rather than for military purposes..
There had been problems experienced by target shooters using RG L42A1 target ammunition in new competition barrels with tight chambers which had been proofed for .308 rather than 7.62mm ammunition and there were concerns about high pressures.
Radway Green manufactured an inspection version of the L42A1 ball round to tight tolerances using the same 155 grain bullet but without charge or cap which could then be used to test rifle chambers. Apart from the empty cap chamber there was no external identification except on the first batch produced. These had the headstamp "INSP RG 99" but the later batch had a normal L42A1 ball headstamp.
