7.62x51 has max 50,000 psi
.308 win max 62,000 psi.
They are not the same. NEAR SAME DIMENSIONS, but different pressure curves. You can safely shoot 7.62x51 out of .308win guns as they are lower pressure bullets, but you CANNOT shoot .308 win out of guns chambered for 7.62x51 ammo. They are not designed to handle the higher pressure rounds. You may get lucky and haven't blown your face up, but IMHO, its only a matter of time before you chamber a TOO HOT load of .308 win and surpass the 7.62 chambers upper limits. Just a tidbit I thought should be passed on, as I see way to much confusion about this caliber. And with the proliferation of surplus 7.62 guns on the market, it would only be too easy to make this mistake. Check the specs online with a google search and see the cartridges compared side by side. There are slight differences that are very important to understand.