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
Samuel Colt be an inventor as opposed to a "medicine man", Colt made arrangements to begin building guns using proper gunsmiths from Baltimore, Maryland. He abandoned the idea of a multiple barreled revolver and opted for a single fixed barrel design with a rotating cylinder. The action of the hammer would align the cylinder bores with the single barrel. He sought the counsel of a friend of his father, Henry Leavitt Ellsworth, who loaned him $300 and advised him to perfect his prototype before applying for a patent. Colt hired a gunsmith by the name of John Pearson to build his revolver.