The 44 Colt cartridge was developed by Colt’s Patent Firearms for use in cartridge revolvers based on the 1860 Army percussion revolver. The cartridge was briefly adopted by the United States Army, around 1871. The Army used it until 1873, at which time it was replaced by the better known and more powerful .45 Colt cartridge used in the recently adopted Colt Single Action Army revolver.
The .44 Colt was made for use in the Richards-Mason conversion of Colt’s 1860 Army percussion revolver. The conversion process involved boring through the chambers of the obsolete cap and ball revolvers and adding a breech-plate with a gated loading port to enable them to chamber centerfire metallic cartridges.
This process left a chamber of uniform diameter, with no step at the front. Thus the bullet and the brass case were made the same diameter, .451-.454 in, with a short “heel” section at the base of the bullet of smaller diameter inserted in the mouth of the case, similar to the construction of .22 rimfire ammunition.
Modern .44 Colt ammunition is dimensionally similar to .44 Special with regard to bullet diameter and case width, the main exceptions being the shorter case length and smaller rim diameter.