The old huntsman had 2 styles of breachplugs. The first style was threaded and quite secure. The later style was O ring. But if the breachplug was drilled out without harming the threads, a barrel lug can be silver-soldered in place and a new breachplug installed, (if everything else is ok). I had one of the later kinds, (.58), and while it was accurate enough to graze a squirrel's head without damaging the meat, (still have the hide from that one), it seemed every time I went for a deer, I got jinxed! Never thought about a shotgun primer. But I never liked the O ring system. Have a friend with one who snagged a cap closing it. He got off lucky with slight powder burns. "Wall-hanger" is a good choice!