Maybe a rifle that's not a bolt action. If caliber and use of those calibers is already covered, perhaps the type of rifle is more in parallel to what you want to do. Lever action, auto or Single Shot. If for example the 308 covers all the needs for him and he has a few 308s it may be more appreciated to buy a 308 in a lever action or a single shot. Think "gun" not "cartridge".
In fact you may also consider handguns and shotguns.
He has a bunch of handguns, although that is a good idea.
