Colt Walker of Texas had been the major purchaser of the early Paterson Holster Pistol (No. 5 model), a five shot cal .36 revolver, and Samuel Walker became familiar with it during his service as a Texas Ranger. In 1847, Walker was engaged in the Mexican-American War as a captain in the United States Mounted Rifles. He approached Colt, requesting a large revolver to replace the single-shot Aston Johnson holster pistols then in use. The desired .44-.45 caliber revolver would be carried in saddle mounted holsters and would be large enough to dispatch horses as well as enemy soldiers. The Colt Walker
Colt M1892 Colt M1892 The M1892 Colt Army & Navy was the first general issue double-action revolver with a swing-out cylinder used by the U.S. military. In 1892 the gun was adopted by the Army in .38 Long Colt caliber, and the revolver was given the appellation New Army and Navy. Initial experience with the gun caused officials to request some improvements. This would be an ongoing condition, resulting in Models 1892, 1894, 1895, 1896, 1901 and 1903, as well as a Model 1905 Marine Corps variant. The revolver featured a counter-clockwise rotating cylinder, which could be opened for loading and ejection