RE: small gun bigger than .243
My son is 14 and slight of build but he handles a .308 just fine. If you can shoot a 12 ga shotgun, you can handle more recoil than most hunting rifles will throw at you. The .308 is very good for deer and can be used for elk. Probably most bear as well (not browns or grizzleys) I would guess. You can shoot cheap military ammo or shoot light magnum ammo for hunting big stuff.