Does anyone have a clue what this is?

[SteveNY]

So, my father-in-law has this old ML laying around... I never saw a rifle with the percussion cap and hammer underneath. No forestock... Nothing engraved on it anywhere. No names, no initials, just nothing. Looks to be a .45

[Four Seasons]

No clue but what a cool find. Man can you imagine back in the day. Big ole Grizz comin down on ya and the cap falls off being on the bottom!  Man, Folks had to deal with some stuff back in the day. 

[airedale]

It appears to be an original under hammer muzzleloader, can't tell the make of yours but I remember seeing replica rifles and pistols of that design for sale when the muzzleloading craze first started taking hold 40 or 50 years ago. I believe Navy Arms sold some under hammer firearms made by Hopkins & Allen. It is a neat old piece for sure.

I found a photo of a replica Hopkins & Allen and posted it below

Al

Edited April 7 by airedale

[Robby]

If you post this on the https://www.americanlongrifles.org/forum/ I'm pretty sure there will be some pretty concrete answers.

Robby

[POLLACK]

Numerich Arms

West Hurley Ny. 
 

[New York Hillbilly]

That’s for guys who like shooting while laying on their back. lol

[Daveboone]

Underhammers were actually relatively common...not as much as regular side hammers, but the nipple fired directly down to the charge...not deflected in the drum like most sidehammers, so more reliable ignition. I always wondered if there was a problem with the primers falling off though.