Mr. Scott:
Your gun appears to be an A Grade H&R, or the finest they offered (similar pic attached from collection of H&R past president). Your's is in exceptional condition and is one of the VERY few guns of this grade ever made. It is RARE!
These guns were made on the 2nd Floor of H&R's plant by workmen who were either brought over from the UK and/or trained by UK craftsmen. The guns were produced under the personal guidance of William and Edwin Anson.
The basic bits for early guns may well have been shipped over from Birmingham. Especially the frames. H&R was the SOLE licensee of the A&D action in the US. And their license prevented Parker from gaining a similar license... so Parker made it's own unique hammerless double.
The full story of these guns, including photos of guns like yours (plus Bachelder's), will appear in my upcoming book,
Birth of The Boxlock. The Untold Story of Anson & Deeley. Out soon from Mowbray Publishers.
gunandswordcollector.com