I have an 1861 Colt Navy reproduction revolver. I bought it used and it was registered and advertised as an Uberti. The serial number was N 19xx. other than the two standard Gardone proof marks and the year code XXIV (1968) it was unmarked. When I tried to swap out the cones I was surprised that the only ones that screwed in were the same as I was using for Pietta revolvers. Somewhere I had read that before Uberti made parts for the Series II Colts everyone in Italy used the same cone size. It seems that Uberti had to accomodate the origional Colt thread, and never went back.
Last year I was talking to the Stoeger parts guy for Canada, and he allowed as this was likely. So seeing your revolvers with few markings other than the proof marks rang a bell. Most of the marks we are used to seeing on these revolvers must have come later. Uberti sold directly to Canada and the U.S. rules for marking may not have applied, either.
I also ran into a glich when I tried to shoot it with TRESO cones, and it jambed up by failing to have enough room to allow the nipples to rotate with caps on them. I emptied that cylinder by fitting it on my Uberti 1851, it went like it belonged there. Later I re-installed the cones that came with the 1861. Then I noticed that the unknown to me prior owner had installed high quality cones that worked perfectly with the Remington #10 caps I was testing. So, no need to fool around with the Tresos.
This was a bit of a Hijack, but shows how some older revolvers can surprise us.