what are you asking about? accuracy? trajectory? ballistics? i duno why everybody compares anything you post here about performance on deer even if deer isnt mentioned in the post..unless your a bad dude your not going to use a ar-15 in either of them rounds to deer hunt.....i know a few guys that use a 223 and love it but they hunted all their lives and are what i would call a bad dude..what do u want are u wondering about the 223 is a good bit smaller bullet wise than the 223...and ammo is easier to find for it...a good 7.62x.39 is ahrd to find...u can find a good premium 223 round easily though....