Reportedly 2,100 of these Colt Model 1860 Richards-Mason conversions were manufactured circa 1877 and 1878 as cartridge revolvers using a mix of percussion revolver parts on hand and newly fabricated components. They are one of the scarcest Colt cartridge conversion revolver variations and were manufactured concurrently with the famous Colt Single Action Army but were more affordable options and are believed to have seen extensive use in the West. The revolver has the distinctive breech plate without a rear sight, a "7023" marked loading gate with external spring and a hammer with the added centerfire firing pin and notch rear sight. The ejector rod and housing are mounted to the right side of the barrel. The top of the barrel has the one-line New York address. The two-line 1871 and 1872 patent dates are on the left side of the frame stamped over traces of the original "COLT'S/PATENT" marking, and "44 CAL" is on the left trigger guard shoulder. It is fitted with a varnished one-piece walnut grip marked "0239" in the rear mortise.

Fine with 40% original blue and casehardened finish, smooth gray and brown patina on the balance, mild dings and scratches, and hammering wear on the butt. The replacement grip is very good and has a spliced repair at the toe on the left, mild edge wear, and some flaking of the varnish. Mechanically excellent. This is both an attractive and scarce Colt Model 1860 Army revolver conversion.