The basis of this design was patented in England in 1851 by Robert Adams as well as improvements by Lt. Beaumont. They are much sturdier than Colt's multi-part, open top revolvers due to the single casting forming the barrel, frame, and grip frame. It was Adams' design that is often credited with forcing Colt to close his London factory. The Massachusetts Arms Co. received a contract to manufacture 500 of the larger belt/navy revolvers for the U.S. government in 1857, and also produced 4,500 these pocket models for the civilian market in .31 caliber, the same as Colt's ever popular Model 1849 Pocket, up until 1861 when they shifted focus to Maynard carbines under Civil War contracts. It has a small cone front sight, "MADE FOR ADAMS REVOLVING ARMS CO. N.Y./BY MASS. ARMS CO. CHICOPEE FALLS./PATENT MAY 3. 1853. JUNE 3. 1856. APL 7. 1857." and a notch rear sight on the top strap, a loading lever on the left side of the barrel, small sliding safety on the right side of the frame below the hammer, the serial number on the left side of the frame and cylinder, and a checkered walnut grip.

Very fine overall with 85% plus original bright blue finish, minor oxidation, most of the loss concentrated on the trigger guard and cylinder, crisp checkering on the very fine grip, distinct markings, and minor handling and storage marks. Mechanically excellent.