Welcome from the Fort Sumter and the Fredericksburg forums.
I'm not sure what maker/model you have there, but those most knowledgeable than me (which is almost anyone) will be along to comment soon. It looks like the loading lever is missing unless it's be converted from percussion to cartridge. The large open loading chamber throws me off.
The cylinder is engraved with images of a wolf, bear, an Indian, a bullet firing, and arrows. The butt is stamped "491" then underneath the barrel it's stamped "968" and "491".
It is a conversion from a percussion revolver to a rimfire cartridge. The wedge in the hammer will be the striker and there are definite signs of a rammer under the barrel, Colt-style. A loading slot is basically an enlarged cap cutout. Only a guess, but looks like a Union Arms Co piece (sherriff model shown)
The cylinder is a new-made one and it looks like the area under the barrel has been cut back to remove the holes for the rammer pin as well, but retaining the serial number. The first part of the serial was under the rammer axis pin and was rounded out to take the rammer. This was quite common . I note that Hopkins and Allen converted these pistols, but I suspect it started out as a Union Armss piece. Can any one trace the serial number to Union Arms?