I had a steel frame, .36 1851 Navy with a brass guard and back strap - it had the same identical markings as this one does. I disassembled it, went over it with a fine tooth comb and never could find a manufacturer's mark on it. The quality of the brass castings was better than this one but overall, if you put the two side by side, they would look like twins with the exception of the guards and backstraps. I believe the date code on mine was the same as well. I did some horse trading in the 70s to get it and it was new but didn't have a box or paperwork with it. I traded it off this last summer towards a 38 spl Colt that I wanted as I have other '51s that I liked more. It still remains a mystery to me as to who made it other than I'm sure it was Italian. I have several ASMs from that time period and the fit/finish was much better on those but who know? I always figured it might be a Pietta but that was a stab in the dark. Good luck on this one - I hope you're able to find something out on it. Enjoy!