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 Model 1855 Sidehammer Pocket Revolver in the design of the Colt Army Model 1860, the Colt Navy Model 1861 and the Colt Police Model 1862. In 1855 the Sidehammer was the first Colt's solid-frame spur-trigger gun. This anatomical characteristic was taken again when the three models of the Colt Derringer started production in 1870. For the two first models production lasted in 1890, and the third model ended in 1912 (until it was re-released in the 1950s for western movies, under the name of fourth model Colt Deringer). But in the Colt Deringers the solid-frame spur-triger design was still present in the patent when Colt's