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
.320 Revolver .320 Revolver Also known as the .320 European or .320 Bulldog, this revolver cartridge was designed for the Webley Bull Dog pocket revolver in the 1870s and similar revolvers made in Belgium that followed. The round was manufactured until the 1920s and was briefly made by Fiocchi in 2015. In Brazil, both guns and ammo (double-barreled, side by side pistols) was made up to 1960s. Amadeo Rossi made his Model 8 "Garrucha" in .320 from 1950 to 1962. The .32 Short Colt was based on the .320 but had a different sized rim. On some guns the .32 Short Colt