If he can handle the recoil of a 180 grain load out of a 308 and there’s NO recoil in a hunting situation then worry more about dragging a moose carcass out of the woods if he shoots one. I let my 12 y-o grandson shoot 225 grain 338-06 at the range and he handled it easily. But I wouldn’t want to have to handle anything bigger than a deer with just him helping