re: Looking for a deer rifle for my son

Dunno about .223 for use by a kid. Depends upon:
1. the average size of deer you expect,
2. the distance you expect the shots to be, and
3. how accurate the kiddo is

I've always used .223 on deer, but my shots are short to medium range. I do head shots at 40 yards and under. Over 40 yds, shoulder shot (not behind the shoulder, but actually through the shoulder). Never shooting more than 175 yds (and only on a smaller deer at that range)

You're the Dad and you know your son and the situation better than anyone. The .223 will cut the mustard depending upon the circumstances.

Though I like and use .223, a .243 will offer a greater margin for error.