The ONLY thing similar is the bullet diameter. The .308 (7.62X51) outperforms the 7.62X39 in every category. Faster, flatter, more powerful, and WAY more accurate. You can check out ballistics tables at all of the major ammo manufacturers' websites. Remington, Winchester and Federal all have ballistics tables. The 7.62X39 is closer in performance to the .30-30.