Colt began work on the revolver in 1871, and submitted a sample to the U.S. Army in late 1872.

The .45 Colt replaced the .50 caliber Model 1871 Remington single shot pistol and the various cap-and-ball revolvers converted to take metallic cartridges in use at the time.

This resolved the Army's ammunition logistics problems, but there were still plenty of the longer Colt-length cartridges in circulation once production ceased.

The original black-powder loads called for 40 grains (2.6 g) of black powder behind an Ogival & flat nosed 255-grain (16.5 g) lead bullet.

However, this load generated too much recoil for the average soldier and was, after a few years, reduced to 28 gr (1.8 g) of black powder yielding 855 ft/s (261 m/s) in Army tests.

Then, the introduction of the Schofield revolver with its shorter cylinder, quick loading "Top-Break" frame, and chambered in .45 Schofield caused a problem for the Supply Corps in that they now had to supply two different types of .45 Caliber revolver ammunition.

Further troubles were caused by the fact that the Schofield cartridge rim was too wide to load into adjacent chambers in the colt cylinder, turning the Colt into a three shooter (being able to only place a round in every other chamber), if the wrong ammunition was sent to that particular outpost.

So, the Army came up with a short case narrow rim cartridge that only held 26 gr (1.7 g) of black powder that could be used in both revolvers.

[6] Because of the power of the 40 gr (2.6 g) of black powder and its excellent accuracy, the .45 Colt was known as a sure man stopper and horse killer.

[7] According to rumor at the time, this was owing to early .45 Colt cartridges having a very narrow rim that caused ejection issues from a rifle chamber.

Thus lending more credence to the rumored basic problem with Colt's revolver cartridges when used in rifles.

[9] Some handloads and factory-manufactured cartridges put this round in the same class as the .44 Magnum, using specially made revolvers.

[9][10] These loads cannot be used in any original Colt Single Action Army or replica thereof, such as those produced by Uberti, Beretta, the Taurus Gaucho, or the Ruger New Vaquero, as these guns are built on the smaller frame with thinner cylinder walls.

Colt .45 revolvers made until early WWII had barrels with .454" groove diameters.

[11] Speer handloading guidance states that the loads they show should be used only in handguns made specifically for modern smokeless powder.

[11] In a section specifically titled "45 Colt for Ruger or Contender only" Speer makes reference to velocities up to 1,300 ft/s (400 m/s) with 200 gr (13 g) bullets.