Rifleman Q&A: Why Didn't The U.S. Army Issue .45 Auto Rim?

posted on April 22, 2021
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
rimd.jpg

Q: If the .45 Auto Rim cartridge doesn’t require the use of a cumbersome half-moon clip in order to be ejected from the Model 1917 Colt and Smith & Wesson revolvers, why wasn’t it issued to our troops armed with M1917 revolvers during World War II?

A: The answer can be summed up in one word: logistics. Having two cartridges of the same caliber that could not alternately function in both the U.S. M1911A1 semi-automatic and the S&W and Colt M1917 revolvers would have been a recipe for disaster.

This situation first surfaced in World War I, when M1911s couldn’t be produced fast enough to meet demand. Consequently, the Smith & Wesson Second Model Hand Ejector and the Colt New Service with factory chamberings in .45 Colt were drafted into service.

The only problem was that even with minor cylinder modifications to accommodate the .45 ACP round, the rimless case of this cartridge provided nothing for the extractor of the revolvers to engage, which meant the spent .45 ACP cases would have to be punched out individually, a time-consuming endeavor, especially during the rigors of battlefield conditions.

As covered in Bruce Canfield’s “Valuable Service: The U.S. Model Of 1917 Revolvers," that dilemma was solved when Smith & Wesson came up with a half-moon metal clip that held three rounds, with two clips being required to load six cartridges. (They were supplied for use in Colt 1917 revolvers as well.) With the .45 ACP rounds affixed to the half-moon clips, they ended up being very effective speed loaders.

After the war, thousands of surplus M1917 revolvers were sold to civilians. Complaints from shooters about the inconvenience of having to use half-moon clips resulted in the Peters Cartridge Co. introducing the .45 Auto Rim cartridge in 1920—a rimmed version of the .45 ACP that did not require half-moon clips to facilitate ejection.

At the outbreak of World War II, history repeated itself, with Colt and S&W Model 1917s again being drafted into service. But although the .45 Auto Rim cartridge was available, it was much more convenient to simply use the .45 ACP in both the Model 1917 revolvers and the U.S. M1911A1, to prevent any mix-ups by G.I.s on the front lines.

Latest

NRA Supports Hunters For The Hungry Programs
NRA Supports Hunters For The Hungry Programs

NRA Supports Hunters For The Hungry Programs

In 2025, Hunters for the Hungry programs across the United States will have extra support from the National Rifle Association, thanks to NRA Foundation donors.

Preview: Hornady Security RAPiD Safe Night Guard

The latest security product to leverage the company’s RAPiD Safe touch-free radio-frequency identification (RFID) technology, Hornady Security’s Night Guard is a ruggedly built handgun safe sized perfectly...

Hecho en México: The Mendoza RM22 Rifles

Mendoza Firearms claims that its RM22 rimfire rifle is the first indigenously produced rifle to be exported to the United States.

Preview: MGE 1911 Grips

Mammoth Grip Exchange is a small startup company that specializes in crafting replacement stock sets for M1911-pattern pistols in a dizzying assortment of exotic materials...

Gun Of The Week: Mossberg 990 Aftershock

For this Gun Of The Week episode, American Rifleman staffers hit the range with the Mossberg 990 Aftershock, a non-NFA, shotshell-firing firearm that provides plenty of power in a compact package.

The Armed Citizen® Nov. 14, 2025

Read today's "The Armed Citizen" entry for real stories of law-abiding citizens, past and present, who used their firearms to save lives.

Interests



Get the best of American Rifleman delivered to your inbox.