One also wonders how many gunsmiths relied upon the jeweller two doors down the street, to engrave the guns he made. We may never know for sure.
I have two other nominees for you, both of whom ended up way out here on the frontier, at a very early date. They are: Philip Creamer, from Taneytown, Maryland, who arrived in St. Clair County, Illinois, circa 1806. Creamer made sets of pistols for such notables as Andrew Jackson, John C. Calhoun, and others. The engraving on his pistols particularly, is second to none.
The other nominee would be John Small, born in Ireland, believed to have worked in Virginia, before his arrival in Vincennes, Indiana, during the 1780's. A silversmith as well as a gunsmith, Small's engraving is superb, along with all of the other details of his work. Small made rifles for such notables as Col. Francis Vigo, William Clark, and Pierre Menard.