calm your heart down a beat or two J.W., Dixie Arms sold a swivel breech gun, made by .....scrscchkttzztffztt, darn brain fart again, aww crap, they also made an under hammer percussion
boot pistol, and rifle.... Can't think of it at the moment. Ahhh, power up, it was a Hopkins and Allen. The rifle was called a buggy gun, and the pistol was a 10 inch barrel boot gun. I almost bought one, back in the early 70's, but the thought of the cap falling off of the upside down hammer system, and how to safely cock it, by turning the gun up, or not, so I did not. But that might be what the guy's father had. But whatever it is, let us know. Good luck, and I have my fingers crossed for you, that it is an original. I don't know if Dixie still sells them or not, or if the H&A company is still in business. I doubt it.
Wayne