Most .303 inch ball bullets carry a manufacturers code impressed in the lead of the base. The purpose of this is to identify the manufacturer in case of problems , for example a batch of ammunition failing accuracy proof or a serious weapon malfunction.
This is needed because in wartime components are moved around factories and the factory showing on the headstamp may not have made the bullets or for that matter the case. Remember the headstamp was placed on the .303 case when it was loaded and necked, not when it was made.
Examples of the codes are a star or a broad arrow for Royal Laboratory, K for Kynoch, E for Eley etc. There is a full list in my .303 identification book.
Similarly, from about 1940 (with the expansion of the Ordnance Factories) the maker of the .303 case stamped their identifying code on the inside of the case between the fire holes.
Prior to this at the end of the nineteenth century a different system was used. You may have seen .303 rounds with a numbered headstamp, e.g. 4 C VI. These represent cases made by private contractors for supply to RL who then loaded them. Similarly, there are cases with both the R^L headstamp and a number, e.g. R^L 5 C II. These are cases made and loaded by RL from metal supplied by contractors. Thus the ammo could be identified by the headstamp:
R^L only - made and loaded by RL from RL metal
R^L and number - made and loaded by RL from contractors metal
number only - loaded by RL into contractors cases.
Going back to the original question, the same system of ball bullet and case marking will be found on .5 Vickers and some other calibres. Obviously the markings cannot be used on tracer and incendiary bullets.
The Germans also marked the base of their 7.9mm bullets in a similar way at least up to the end of WWI.
Hope this helps,
Regards
TonyE
