RE: managed recoil ammo
I bought some of the Remington Managed recoil and federal low recoil rounds last year and shot them in my wifes new 30 - 06. I wanted to see if they really were what the companies claimed they were. I can say that the don't print exactly the same as the full power loadings, but they were close and required only minor adjustments of the scope settings. And, as far as the power goes, they were pretty much equal to a .243 in recoil. So they lived up to the hype as far as the recoil goes, and they are good out to just over 200 yards. I think it would make a fine gun for your son, with either of those low recoil loadings.
But , since you did not say what kind of gun you have, be aware that the reduced powder charge in either brand is not enough to cycle a semi-automatic rifle and the case will hang during ejection. If it is a bolt action, you are in good shape.
Good luck and Good hunting
God Bless