The stab crimp varied from lines to three round punch marks, and during and after WWII they were sometimes omitted entirely. That may well have been based on the type of bullet used. But the 1929 British Text Book of Small Arms is quite clear in saying that "The bullet is secured into the case by three indents made in the case, the metal of the case being pressed into the cannelure."
Since that was before adoption of the BREN gun, it is reasonable to suppose the process might have arisen out of the cartridge handling by the British Vickers/Maxim gun in WWI. There is no mention of this being special, or limited to machinegun ammunition, nor indeed is there any indication of any separate manufacturing procedures for machinegun ammunition; presumably, any .303 ammunition would be safe and correct for any weapon of that caliber.
Last edited by James K; April 28, 2013 at 11:45 PM.