I agree with the other posters saying the 6.5 Creedmoor would be a good choice. So would other rounds, like the 243 Winchester. Can you borrow some rifles from friends for your son to shoot before you buy? Do you handload? If you do, you can load ammo for a number of chamberings to suit a young shooter. If you don't handload, the 6.5 Creedmoor is even more attractive as there are lots of accurate ammo choices.
