I feed a lot of South African 7.62 X 51mm to an M1A and an L1A1.
Which brings to mind: Thou shalt not covet thy neighbor's M1A; thou shouldst spring for thine own. Preban 7:62.
OK I recind my semi-expert status. I was looking at some rifles and ran into 7.62x39 and 7.62x54. HELP! I am going to assume that the 762x54 is the nato round but then I saw an SKS 762x39 so I are cornfused agin'!