My bet is that if you remove the sight there will be an "A" stamped inside of a shield on the bottom of the sight base, making it a "Riflesmith" sight made in Sheridan Montana by Axtell Rifle Company. Midrange. And the finish looks to be pretty well worn as these were meticulously polished and nitre blued. These sights will develop "Brown" spots that look like rust(but cannot be removed with "Big Frontier 45"
http://www.big45metalcleaner.com/Customers/ or steel wool) if not cared for (cleaned and oiled) properly. In your original question on the other thread you stated it was color case hardened, it is/was not case colored. What you have is blotchy blue/gray remaining finish. It would look great on a heavily "Antiqued" Quigley model Shiloh.
Chris
