I've been reading through freerangeYoda's work and I'm not sure if he or anyone else has come to any conclusions on this subject. I guess I am also guessing that both of these are better than any FMJ bullet.
I was also looking through this http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#7.62x39
I was also looking through this http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#7.62x39