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The British Purchasing Commission placed orders with Remington in 1940 and 1941, but then the Lend Lease Act was passed and the US government took on the responsibility for supplying ammunition. Prior to that we had also purchased .30 and .50 ammunition direct from the US government.
Total orders were 395 million ball, 95 million AP and 40 million tracer. There were also un unknown number of incendiary.
We never made .30-06 in the UK during the war except in trial lots. There were plans to do so and ROF Hirwaun were given large orders for tracer , AP and incendiary, but in the end the supply from the US proved adequate and there were higher priority calls on UK manufacturing resources. The orders for tracer and AP at Hirwaun were cancelled, but some incendiary was made. It is believed that these were probably loaded in American cases, although Hirwaun did make some experimental cases.
The principal demand in the UK for home produced 30-06 had been for incendiary for air service, as the British design, based on the .303 B Mark VII, was considered superior to the US M1 incendiary.
There were also many thousands of drill rounds made, mainly for Home Guard use, from fired US cases.
Regards
TonyE