That style of lock was used on Syracuse L.C. Smith's, from a patent date of November 27, 1883 by Alexander T. Brown, 289062, Side Lock System, L.C. Smith Hammer Guns. It was also the same type used in English hammer guns. In the picture you can see how close they match.

https://imgur.com/a/5mxLanJ

I forgot how to post picture without going through this step.


David