Hey, look, guys, the subject is recoil and an 8-year-old kid. Noise is a health factor, also--which is why I'd disapprove of the use of a muzzle brake for a youngun's hunting gun.
I thoroughly enjoy my .243 (a couple of dozen tagged bucks) and have done a bunch of shooting with the Swift and the .22-250. But for what's wanted for the youngun, modern bullet development has made the .223 a decent deer-killer--and it's history is irrelevant to this thread.
An added benefit, of course, as we've all commented many times, is the relatively low cost for practice as compared to the factory ammo of other cartridges.
You're from BATFE? Come right in! I use all your fine products!