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 Dragoon Revolver from exploding when fired, unlike the risk that had been demonstrated with the Walker revolvers. In the troublesome events that led to the Civil War, Colt Dragoons became extremely popular. In the beginning Colt Dragoon Revolvers were issued for the U.S. Army's Mounted Rifles. They were carried in pommel holsters on the saddle. The Colt Dragoon Revolver gained popularity among civilians in the Southwest where many had served in the Mexican–American War. The Dragoon became a master weapon for civilians who hailed it as a powerful weapon of the time. Famous users included Joaquin Murietta, the California bandit, Charley Parkhurst,