I wouldn't rule out middle Tennessee, maybe white or Jackson county, probably 1830's?? Not sure about that buttplate with the cutout, could be a replacement. The molding line on the forearm is also a bit odd to my eye, looks like a "customer modification".
That said, the buttstock shaping is very similar to an earlier iron mounted rifle by unkonwn maker signing G.B., classified by W. Gusler as SW Virginia or thereabouts. I would look at the hardware on that one, though the buttplate on this one leads me to expect much later origin if it's original. Would be nice to know if there are signs of a weld broken on the return or if the original was two piece.
Sadly the tang style could have been a clue. If narrow and pointed, I'd lean toward SW Va, but if it flared Midway and tapered back to a point, I'd lean toward middle Tennessee and later.
PS I think the buttplate return is original almost certainly.