Best source to start with is the book, American Gunsmiths, or Early American Gunsmiths 1650-1850. The first is a source of every gun maker who ever set up shop here. If he's not in there, he might not be found. The second covers just the time period specified. It's only about $8-$10 at Amazon, while the first one I check at the library, as it can run several hundred dollars to buy!
Hope this helps.
