.44 RF. 7.5" round barrel. SN: 5013 (mfg. ca1872). Blued and color casehardened finish, one-piece walnut grip. Single action cartridge revolver with loading gate and six-chambered smooth round cylinder. Barrel marked in a single line - ADDRESS COL SAML COLT NEW-YORK U.S. AMERICA -. Lower left side of frame with two date in two line 1871 and 1872 patent markings. Matching external serial numbers, no number present on wedge, cylinder or in grip. No scene on cylinder. Grip with added crude checkering. Fixed notch rear sight on rear of barrel, forward of barrel and German silver blade front sight. Richards-Mason type ejector rod. The 1871-72 Open Top was Colt's transitional large bore cartridge revolver that they produced immediately prior to the Single Action Army. Only about 7,000 of the revolvers were manufactured circa 1872-1873 and production was terminated upon the launch of the 1873 SAA. Many of these guns were sold off to Mexico and Latin America where the .44 Henry Rimfire remained a viable and popular cartridge well into the last quarter of the 19th century. The Open Top is a difficult gun to acquire in any condition and this is a reasonably crisp example, despite its lack of finish.