Gary - excellent descriptions on the geography of Virginia. The valleys and the rivers were the paths of exploration, war, trade and settlement and the routes by which the gunsmiths and their products moved, both with their customers and connecting to new customers.
In addition to the geography, another thing that muddies the waters when trying to learn about longrifles made in Virginia is the evolution of the counties - how some counties were created, then subdivided time and time again, so that period descriptions somtimes indicate two widely separated areas as being in the same county whereas today they are in different counties and would be regarded as different styles/regions/schools.
To me, one of the most fascinating, yet currently most misunderstood, regions is the area where southwest Virginia, northwestern North Carolina, and upper east Tennessee meet. Settled before the Revolution, one can imagine the mixture of gunsmithing influences moving through this region in the 1770s-90s.
Heinz - good to see you here old friend!
Gary hit the nail on the head with the stepped toe issue. There are surviving iron mounted guns from the 1790s that appear related stylistically to the brass barreled rifle, such as the MESDA gun and several others Wallace has featured in his articles. Good luck on your project.
Guy