Originally Posted by Sevens
The rear sight doesn't look like most S&W adjustable revolver sights that I'm familiar with...I'd say that from the side it almost looks like a Millett adjustable sight.
Bingo. Millett used to make a terrific rear sight for S&W revolvers, but stopped a few years ago. I have one on my 1° match gun, and have been looking for another. They're tough to find nowadays, so the OP ought to at least be aware the rear sight itself is somewhat desirable. Good call, Sevens.