The thimbles do have flats filed in them as I recall. The file work on the mounts on this rifle is all neatly done - not overdone - just looks very efficient and confident)
Ron Borron's drawing (which is what you have from Log Cabin Shop) - does call it an Early Virginia Rifle. Back when the drawing was done, Myron Carlson would copy rifle hardware and Ron would do the lind drawing to accopmany it and they would sell the plans and hardware together. Sometimes Ron drew them exactly like the original, and some he modified to show the rifle with available locks that would work. There are two versions of the drawings for this rifle - one with original lock and drop, and a later revised one where he modified it with a Durs Egg and took out a little drop. Myron mostly copied later Tennessee and North Carolina mountain rifles and I think that at the time they copied the Bogle its early appearance and dissimilarity to what we think of as the classic "mountain" rifle led them to speculate it might be a Virginia gun. I also recall at the time the owner did not want the maker's name revealed. This was all, I beleive, before Wayne Elliot's great research and article (which you can see in the Virtual Museum) indicated the rifle was actually probably made in Tennessee.
This is also the only known rifle that I think everyone agrees was made by Joseph Bogle. There are two others I know of - one in a private collection and one or two in Jerry Noble's books - that some say yes, some say no. Some may have been made by the nephew, also named Joseph.
Guy