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 Walker martial pistols and revolvers, was a practical weapon out to about 100 yards. The Colt Walker holds a powder charge of in each chamber, more than twice what a typical black powder revolver holds. It weighs unloaded, has a barrel, and fires a .44 caliber ( diameter) conical and round ball. The initial contract called for 1,000 of the revolvers and accoutrements. Colt commissioned Eli Whitney Junior to fill the contract and produced an extra 100 revolvers for private sales and promotional gifts. Notable recipients include John Coffee Hays. Colt commissioned New York engraver Waterman Ormsby to etch a scene