There is also a difference in the Grip to Frame transition. That may also be a dating clue.
I noticed that as well. Actually the grip is also different on the pair. The pair has plain wood grips where mine is inlaid with silver wire. I'm trying to determine if the trigger guard has ever been silver plated giving another clue.
Although the determination of hand engraved vs stamped or even the addition of a silver plated trigger guard could put this into a category of made for the European market that would increase its value significantly, my greatest hope is that it predates the export date of 1790 (probably 1794 really) and that it could date back to revolutionary or pre-revolutionary war time. That would fulfill a dream to own a firearm dated to the revolution.
My gunsmith was closed today, so no luck getting an opinion from him. I'm looking at digital microscopes to aid in getting better pictures of the engraving. Probably a lower end student model and probably a hand held version. All of them come with a stand to steady the instrument. I can see uses for it other than this project.
Lastly, I perceive that the engraving on the pair for sale is not quite as intricate. Does anybody else sense that? Or is that just wishful thinking on my part?
Here is another that is almost a duplicate of mine at the Metropolitan Museum of Art in New that is also missing the "London". It is at:
https://www.metmuseum.org/art/collection/search/29609
And here are some close ups of the engraving on the one at the Met.
Both the pair for sale and the one at the Met appear tao have less intricate engraving. Though I'm willing to accept that is wishful thinking on my part.