The architecture looks strongly southwest Virginia, or possibly over into what is now West Virginia, very similar to some of the late Honaker guns in Wallace's articles. As do the pointed tang and iron mounts. So that would be my first hunch. I will throw one more thing out there though - the comb architecture , pointed tang, triggerguard and iron mounts also crop up on guns by Jerman Jordan who worked in Chilicothe Ohio in the first and second quarters of the 19th century and proably other gunsmiths working on the western fringe of the Appalachian plateau. Not saying Jordan made it, but we should consider all the possibilities. Can't tell if there is really much of a step to the toeline, but the gun is very close to an iron mounted Jordan flint gun, with no buttplate, that I saw at Friendship last summer, but had no step to the toe line.
In spite of this looking like a late gun, the guard is a throwback to what seems to be the earlier style of iron mounts that more or less look like they were emulating the popular brass mounted styles of the time being made in the big gunmaking areas further east and north. As Ian said, these styles seem to predate the more stylized mountain rifle guards of the 1830 and later era and I tend to associate them with the idea of a migratory gunsmith trained somewhere down in the Shenandoah Valley or other nearby area who then moved south and west into the Virginia or east Tennessee mountains or beyond, following the frontier. Similar guards can be seen on the Bogle rifle, the guns that Jim Levy posted from the Florida museum, and even one of the probable Gillespies in Dennis' book.
Curly maple was very popular on Appalachian guns - I have seen as many or more mountain rifles stocked in maple as walnut.
This is a neat gun - thanks for posting.
Guy