Eric, I've enjoyed reviewing your rifle several times. When I first saw your posting, based on architecture, tang style, and rear ramrod incised carving, I thought the gun might possibly be from central Kentucky. There were a number of Bartons working in Kentucky, but none match the first initials. I had hoped that perhaps you misread the first or second initial, so that it might match one from Kentucky, but upon seeing your photos, I think you nailed the name.
I have seen a few signed KY guns with the incised lines on the comb that we normally associate with NC guns, and with the single line molding, wavy incised carving at rear pipe, two screw tang, and clean stock architecture it could have come from KY. The patchbox at first glance looks odd for KY, but after reviewing it a couple of times the past week, it could have come from northern KY in the Louisville vicinity. The early boxes used by Moses Dickson of Louisville, who began working there in the early 1820s, have side leaves that resemble these, and even more interesting is the fact that Dickson attached his early side leaves with small brass nails rather than screws. The relatively tight side facing, general stock architecture, and nice ovality of the guard's bow also strongly resemble KY guns of the 1820s. However, KY guns of this era usually had more pointed toes on their butts...and the somewhat primitive engraving is different from what I've seen on KY guns.
I still have a hard time placing this rifle in Indiana, particularly with the somewhat later working dates of our known Indiana W. H. Barton gunsmith. The gun sure has a lot more NC and KY details than Indiana...but then, you just never know fore sure on some of these "different" rifles. If you have my KY book, look at the boxes on the two early Moses Dickson rifles pictured in the "Louisville" chapter in Vol. 1, and compare the side leaves for shape and nail attachment. Shelby Gallien