Depends on what state(s) he'd be hunting in. So far as muzzleloader-only tags, guns that are legal for one state may be illegal for another. Depends on what game he'd be hunting because some states have different minimums for different animals.
Study the rules for muzzleloader-only hunts for the state he'll hunt in. Those will tell you a lot. Don't trust the gun shops to know the rules or to only sell what is legal in that state, ours sell a lot of stuff that don't fall within the limits of the muzzleloader requirements.
In my state, I'd probably get them a Lyman Deer Stalker .50 caliber percussion rifle. There are a few things I don't like but it's pretty close to idiot-proof, legal, and generally sufficient. Plus, with a factory recoil pad instead of a metal plate and a short 24" barrel its a good choice for a smaller shooter you don't want to over burden or beat into a flinching machine with recoil.
Tom
