As Buck pointed out, a lot of Free Mason history originating in Davidson Cnty. and throughout NC, dating well back into the colonial period.
If you examine the negative spaces created in some of the Free Mason symbols and art, it does resemble (somewhat) the shape taken in some of these inlays. Possibly hidden intentionally and designed to be recognized only by the initiated, or to be used only by the initiated. The fourth photo down with the 'curved -V' coming off of a point, might be symbolic of a opening book, a very common Free Mason symbol, as might be a 'straight-sided V, as well. Symbols of rank, or lodge office, or combinations of both, added as well? Owner, or family history may provide a clue to interpretations.
Or, it's just regional art, like the rifle itself, that fortunately has survived.
Thanks and Good luck!