I went the .243 route with my son and it worked out well. Now that he's grown though I think he'd be more happier with a larger caiber. What a friend of mine did seems to make the most sense and if I had it to do over again I'd do it the same way as my friend. What my friend did was buy his son a 7 mm Rem Mag with a muzzle break. In doing it this way the kid could have a rifle with the kick along the lines of a .243 but in a larger caliber, something he wouldn't grow out of.