muzzle loader

My great great grandfather’s muzzle loader has been sitting for years. Looking to shoot it but want to be sure not to damage it or myself. Probably hasn’t been fired in 75 years. It’s a 41” barrel, smooth bore 3/4”. With percussion cap. Not sure if it was upgraded to a shotgun cap or not. It’s...

Pair of antique Hopkins and Allen underhammers .45 cal

I got into a discussion elsewhere about the legality of a muzzle loading recoilless rifle and have tried to read up on the pertinent laws. I feel like I'm missing something so I wanted your all's input on this. Would it be legal to construct and fire recoilless arm that: Is muzzle-loading...