1851 Question

[Cowboy2]

When did they switch over from the original (as I understand it) squareback to the round trigger guard?

 

[Fingers McGee]

The square backed triggerguard was used on the first model Navies from SN 1 through SN 1250; and on the second model Navies from SN 1251 though SN 4200. They went to the small round triggerguard at SN 4201, the beginning of the early third model Navies. The odd square backed triggerguard is found on later serial numbered revolvers due to Col. Colt's penchant for not wasting anything.

 

[Cowboy2]

What would the time-frame be?

 

[Fingers McGee]

1st models 1850/1851; 2nd models 1851/1852; Early 3rd models 1852/1854. Sometime during 1852 Colt switched from square back triggerguards to small round triggerguards.