I've got a 14.5" 7.62x39 upper, with Remington Cor-lok soft points I was un-happy with the terminal performance on a 150ish lb deer. The round did not expand as expected, was a pass through and acted like an fmj. The deer ran approximately 80yds with zero blood trail. Shot placement alone was what put the deer down (double lung). So I know that the cor-lok bullet is a much better projectile than anything Russian made, and if 14.5 isn't enough powder burn for optimal terminal velocity, I would recommend at least 16". Keep in mind the 762x39 was developed for the sks with a full length 22" barrel.