Howdy
There were two distinctly different models of large frame Merwin Hulbert revolvers, the Frontier model and the Pocket Army models, so I am curious which one you have.
This is a pair of Frontier 3rd Models. Easily identified by the long straight grip.
This is a Pocket Army 2nd Model, easily identified by the short curved grip with the 'skull crusher' feature at the bottom of the grip. Do not be confused by the term 'pocket army', these were not pocket pistols. They were just as big as the Frontier models.
The terms 1st Model, 2nd Model, 3rd Model, and 4th Model refer to different features shared by both of these versions of the large frame Merwins. 1st Models had no top straps and had scoop flutes, such as you see on my Pocket Army. 2nd Models also lacked the top strap, but the internal mechanisms were slightly different. 3rd Models had the top strap added to the frame, and 4th Models had the top strap as well as a rib on top of the barrel.
Both of these versions of the large frame Merwin Hulberts were available in single action or double action versions, and both were available with the folding hammer.
Calibre Winchester 1873 was the way MH marked their revolvers that were chambered for the 44-40 cartridge.
The SN for the Frontier Model was on the underside of the butt, the SN for the Pocket Army was on the right side of the skull crusher.
So which one do you have?