The upcoming Cowan's auction has some interesting rifles.

This one is particularly nice IMO.
Looks as though it is a percussion muzzle loader with an internal hammer which is cocked by lowering the "block".
I am not at all familiar with this patent but, man, is it cool!
They say American Primer Ignition (perhaps referring to the patent) but the styling, especially the grip, looks very Scottish to me. Nor do I know why they invoke Nimschke as the engraver

http://www.cowansauctions.com/auctions/item.aspx?ItemId=129212

Also Gibbs and Rigby percussion match rifles in this auction and, sadly, a Rigby 350 double rifle which has been sleeved to 22Hornet...