I assume you're talking about US military 5.56 and 7.62. I know that most of it was made by various US arsenals (Radford, Lake City, Twin Cities) but I know that Winchester made quite a bit of our ammo. It uses what most refer to as "GI brass" USGI 5.56 usually has about 2 grains less case capacity due to a thicker web and thicker walls. Load specs are about 3200 fps for M193 55gr. FMJ using WC844 powder so on the hot side. Anyone who knows better feel free to correct me!
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