I bought a bunch of GI brass that was once fired thru a mg. I cam over sized it and checked all the sized cases in a Dillon case case gauge after I had trimmed to min. and chamfered it.
Any that did not gauge went into one pile and were checked for chambering in my bolt guns, they all chambered. The gauge passed ones are loaded for my AR-10. Works for me.

" Cheapest velocity in the world comes from a long barrel and I sure do like them. MB "