You are going to be busy point out to people that they offered their opinion when it was not asked in a forum.
As for the question, 223 and 22 calibers are on the low end of choices for deer. So my answer to his question was neither is what I would use. If already had the gun, and couldn't afford another, sure 223 will kill deer. It is effected by win, and requires very good shot placement, and patience for that shot.
6mm is probably what most people would say is minimum for deer. AR15s are popular, and people are using them for deer. AR10 would be better for deer hunting.
My choice on calibers, is not an alien idea. I am not the only one to express it. I realize 223s are used for deer in some states. A 243 can be loaded frm 55-105 grain bullets. My newest lyman lists 55 for 223. Probably higher somewhere.
If he is going to use it, I would suggest he get better at reloading, and choice premium bullets. Loading your own increases bullets you can use.
