Looks to me like Shelby pretty well nailed this one down. It has a lot of NY state about it to my eye, too. The gingerbread, notwithstanding, the architecture and the marked lock pretty well underscore that it is an NY gun.
Some things about it that are out of the ordinary: super heavy duty architecture, and the unusually sturdy construction; An oddity is that the lock plate is oriented on a rather acute angle to the usual horizontal plane that most makers seemed to observe. The very short, thick wrist may account for this.
Wouldn't be at all surprised if this gun were not built as a western trail rifle. It would stand up admirably to the rigors of such use. Whether it made the trip or not we won't know, but it would have served well. It may have stayed closer to home and saw use as a heavy duty hunting gun; bears, moose and deer.
Not all Western guns had big bores tho legend says they did. In truth, the largest bored guns were the California Rifles which were made to bring down the CA grizzley bear. The calibers ran from .50 to .65 on the ones I have seen.
Have to remember, too, that eastern gun makers had not been out west and did not necessarily see anything bigger than a .45 as having utility, so they made smaller bored guns. Of course, in St. Louis, they saw things differently.
As to age, this one looks like it could have been made during the period of western expansion and the northern trail began up in NY state running west along the lakes.
Heck of an interesting gun and thanks for bringing it out for us to see.
Regards-Dick
