As you might tell from earlier posts, I am a fan of the "typical" Morrison sidelock mechanism, which I suspect was built by Morrison or a blacksmith in the region (these same sidelocks show up on other Upper Susquehanna guns). This back action sidelock is really interesting, too. The internal main spring is very similar to its external counterpart on the Morrison attributed rifle in the Library. The patent is interesting and I will see if I can find anything in the federal records to confirm that this is a Morrison patent. I only know of one maker with a patent in the Upper Susquehanna (Federick Beerstecher of Lewisburg patented his super(im)posed lock mechanism)
As far as this being a Pennsylvania or Illinois gun, the patchbox is definitely a style that he used in Milton, Northumberland County, Pennsylvania, as it is the most common patchbox design of his competitor, William Filman, who also worked in Milton. Of course, Morrison could have taken this patchbox style to Illinois, but I will leave that to Curt.
