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
.45 Colt .45 Colt The .45 Colt cartridge, which is sometimes called .45 Long Colt, .45 LC, or 11.43×33mmR, is a handgun cartridge dating to 1872. It was originally a black-powder revolver round developed for the Colt Single Action Army revolver. This cartridge was adopted by the U.S. Army in 1873 and served as an official US military handgun cartridge for 14 years. While it is sometimes referred to as .45 Long Colt or .45 LC, to differentiate it from the very popular and ubiquitous .45 ACP, and historically, the shorter .45 S&W Schofield, it was only an unofficial designation by Army