I found the probably SC rifle I was remembering, the one signed Stephen Crain. It's illustrated in Whisker's "Gunsmiths of the Carolinas, 1660 - 1870" and in Jerry Noble's first volume of "Notes on Southern Longrifles". I misremembered much of Crain's history. Seems he is first located in Warren Co. NC which is in the northeast of the state, really on the fringes of the longrifle heartland. Then he appears in Chester Co. SC which, along with York and Lancaster Co. make up what the tourism folks now call the "Olde English District" of the state. Rolling hills rising to the mountains. The King's Mt. Battle was in York Co. Stephen Crain dies in Chester Co (1833), but a son appears later in MS.
Based on the photos in those two books, I'd hazard an association with the Kennedy family of the Bear Creek school, NC. The rifle is iron mounted (I think), stock architecture similar to some of the Kennedy work, captured lid box, simple spear point finial on the box with heart cutout reminiscent of some of the work by Davidson (James River Basic school) in VA. I've always admired the utilitarian style of this rifle. I do not know where it resides currently.