Hi Dennis,
Thanks for posting this. There is a lot of information and documentation on Isaac Price in my book, "The Longrifle Makers of the Mecklenburg School." I have been unable to find a singed rifle by him. I did include photos of two unsigned early Mecklenburg Rifles in my book. The first rifle was owned by John McKnitt Alexander who moved to Mecklenburg County from Cecil County, Maryland in 1764. I believe the rifle was made between 1770 and 1775. John McKnitt Alexander was the Captain of the Mecklenburg Militia who helped earn the county it's "Hornet's Nest' nickname.
The second early rifle in the book is the oldest known example of Mecklenburg School rifle. It dates to around 1780. The rifle is .58 caliber flared to .62 caliber at the muzzle. I think it may have been a militia rifle. I also have an early militia horn found in Mecklenburg County with an unusual screw off base.
Michael