Thanks all--

The more I think about it the more I think a modified 20 gauge shooting slugs with Double triggers would be a better platform to start from.Gonna take some work to get something functional but thats the fun of it all.

The muzzleloader would be tough cause he's into shooting and not maintenance of firearms--

Express sights on a Double slug gun sound more appealing at the moment.Guess he's going to have to EARN that future Double!!