Thank you for the additional information. I finally have my hands on the gun, which is a 12 bore pinfire. To confuse things, the top rib is engraved with a Bridge street address, which there doesn't seem to be any documentation for. My guess is that John had a very short working career (under his own name) and may have been at one or two address for a very brief time. If nothing else, it just adds to the intrigue of these old guns.

“I left long before daylight, alone but not lonely.”~Gordon Macquarrie