Interesting project, we'll help if possible. It would help if we could see photos of the whole gun, both sides and close-ups of all the markings in the metal, cartouches if any etc. I have a friend who is a recognized Colt expert and I'd like him to look but I know he'd want to see more photos. I'm no expert but I've never seen any 19th C. Engraving like that. The font looks mid-20th C. Or later to me, but don't take my word for it. I'm also wondering about the date format-I don't see that date format used in antique presentations but I'm not really confident in my knowledge there; requires further checking.
To Join the Company of Military Historians click here