In my opinion recoil is just a tolerance of what a person can handle and still make a tight group. If the guy next to you at the range is saying I've never grouped my magnum that well his either using the wrong load for the gun or he's flinching. The sound of magnum make most people flinch. I shoot a 300 win. theres not alot of recoil there in my rifle. But the first rifle I bought in that caliber was a remington 700 adl synthetic. I bought it at a banquet one night and holy cow that thing kicked like a mule. Different gun different kind of backwards kick.

As far as kids shooting magnums it would be the individual kid. If after time they still can't group their shots. Then maybe the parent will be wise enough to try something different. Using a percussion or a flintlock muzzleloader teaches the best shooting habits there is. If you can hold your shot for the delay and manage good groups you have proper shooting composure and tolerance. It boils down to the individual child. Notice the word "child". Your kid is not a pu88y if he can't handle it just yet. Let your children make the choice on what fits them. Don't push it on them, we need all the future hunters and pro-gun people we can get in the future.