@jtallen83My reload recipe is as follows: 7.62X51 LC brass, Winchester LRP, Hornaday 150 FMJBT, 42.5 gr. VARGET, C.O.L 2.695" this should push around 2600fps. The .308, which cycled fine, mixed headstamps, Winchester LRP, Hornaday 150 FMJBT, 44 gr. IMR 4895, C.O.L 2 698" primarily used in my 110 Tactical bolt rifle. Never fired steel case ammo, the range sells it, but you can't fire it there.
As shooterrex suggested maybe have the chamber redone with a 7.62 reamer?
@AlbroswiftI agree, military brass is sometimes a PITA to resize. 5.56 NATO was troublesome until purchasing a carbide die set, I still lube the cases before sizing though. I have standard .308 dies, probably need to invest in a carbide set, down the road.