Some of the Tennessee's also curled forward, most of the Bull's guards were built that way. 1/2" is a wide rail, be great if you were able to post some pictures, these gentlemen could probably give you better information.
Not many early southern iron mounted rifles are known, so they don't tend to be wide butted like the PA guns, however a few SW Va rifles are thought to be early and do have heavy features. The Jos Boggle rifle is thought to be fairly early (1790s?) and from TN, I don't know how wide the butt is.