Yes, your only choice is 308 Win.
However, the walls (i.e. neck walls) are generally thicker on military brass. With your average, cheap, regular sizing dies, you'll be working the hell out of those necks sizing them and then expanding them again. Pay a little extra and get bushing dies with the proper size bushing if you want to do 7.62x51 the right way. You'll void a lot of headaches, hassles and broken expander buttons.