[Grizzman]

If the barrel length is 20 inches, then I agree that a max of 250 yards is reasonable.

According to Sierra Infinity, the Federal Fusion 7.62X39 ammo at a starting velocity of 2350 fps drops to 1656 fps and 750 ft lb of energy at 250 yards. While 1000 ft lbs is preferred, the bullets should be soft enough to open up at the reduced velocity to do adequate damage.