As was mentioned once earlier....look real hard at the .260 Remington. It' s 6.5mm bullets come in a fairly large variety. From lightweights meant for varmints up to heavyweights intended for the largest medium game. (In factory ammo it slightly exceeds the grand old 6.5X55.) The recoil is very similar to the .243 Winchester in the .260' s 120 grain loadings. (The 120 grain bullet in the .260 Remington has a sectional density similar to 165 grain .30 caliber bullets....which makes it more than sufficient for deer sized game.) You can have factory loads by various makers in 140 grain as well. Which is a better bullet choice for medium game heavier than the average whitetail. And if you reload there are bullet weights all the way up to 160 grains....(about the same sectional density as a 220 grain .30 bullet). Which makes a very effective short to medium range load for any herbivore on any continent. And with a very flat shooting load in its lighter weights. All of this with very mild recoil indeed!

And as a bonus...there are a number of companies that chamber for the .260 Remington in very short, light, rifles. Remington' s Model Seven in either blue or stainless. Ruger chambers in its Compact (with only 16.5 inch barrel) in blue or stainless and even with a laminated stock. Also a number of other manufacturers chamber for it in other models as well. It is a caliber easy enough for him to handle now...and one he won' t outgrow!

Good luck with your decision!