With him being that size, he'll be fine with a 6.5 Creedmoor, and for factory ammo, that's the best bet. Put a good brake on it and it'll be fine. The Bergara Mark mentioned is a good option among a pile of them out there. I'd go that route before an RPR or some of the others without hesitation. Put the best glass that fits the budget and a bipod on it, get a rear bag and go shoot. Figure out the rest of the support gear as you go to avoid wasting money, plenty of opportunity to try before you buy on that stuff.