FWIW
During WWII the British used pressed in tracer compound on a fair number of its smaller rounds (upto 6pdr at least, maybe larger), sealing the opening against moisture and such with a celluloid(cellulose?) disc. The Americans copied the method for most of their US/UK compatible ammunition of the same types.
During WWII the British used pressed in tracer compound on a fair number of its smaller rounds (upto 6pdr at least, maybe larger), sealing the opening against moisture and such with a celluloid(cellulose?) disc. The Americans copied the method for most of their US/UK compatible ammunition of the same types.