I have the Ruger 77 Mk II heavy barrelled varmint, with laminated stock, in .22-250. Very excellent shooter, has taken many groundhogs. I would buy one again. My brother likes his Savage varmint rifle in .308.
If you're open to considering guns other than bolt actions, look into a T/C Encore rifle in that caliber. This gun can be switched out to a pistol configuration, as well as shotgun for turkey or other upland game, or muzzle-loader. The advantage for your son would be that he can get one buttstock to fit him for multiple shooting situations.