.45 Auto Rim on:
[Wikipedia]
[Google]
[Amazon]
The .45 Auto Rim, also known as 11.5x23mmR, is a rimmed cartridge specifically designed to be fired in 
Loads offered were similar to the standard military loads for the .45 ACP, but with fully lead bullets rather than the full metal jacket bullets used for .45 ACP. This was done to reduce barrel wear in the shallow rifled revolvers in which it was to be used.
The round is currently still in production by Corbon in their DPX and Performance Match lines of ammunition and is also manufactured by Georgia Arms and Buffalo Bore Ammunition.
revolver
A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...
s originally chambered for the .45 ACP
The .45 ACP ( Automatic Colt Pistol), also known as .45 Auto, .45 Automatic, or 11.43×23mm is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After su ...
cartridge.
The Peters Cartridge Company
The Peters Cartridge Company was a company located along the Little Miami River in Kings Mills, Ohio, which specialized in gunpowder and ammunition production. Founded in 1887 by Gershom Moore Peters, the company supplied military ammunition to v ...
developed the cartridge in 1920 for use in the M1917 revolver
The M1917 revolvers were six-shot, .45 ACP, large frame double action revolvers adopted by the United States Military in 1917, to supplement the standard M1911 pistol during World War I. There were two variations of the M1917, one made by Colt ...
, large numbers of which had become available as surplus following the end of World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
.
Two issues related to the use of .45 ACP ammunition in the M1917 revolver led to the development of the .45 Auto Rim. The M1917 had previously been used with half-moon clips that held three rounds of .45 ACP, a rimless cartridge. But if half-moon or moon clips are not used when firing a rimless cartridge in a revolver, the spent cases must be ejected by hand—either by shaking the revolver and its swing-out cylinder or by poking the cases with a rod or field-expedient tool, like a pencil—as the revolver's extractor cannot grab them. The second issue concerned headspace
Headspace may refer to:
Science and technology
* Headspace gas chromatography, a technique in analytical chemistry
* Headspace or ullage, the unfilled space in a container
* Headspace technology, the gaseous constituents of a closed space abo ...
. In revolver cylinders not engineered to allow .45 ACP to headspace properly, as in early production Colt M1917s, the cartridges could slip forward, stopping them from firing. Adding a rim to the .45 ACP cartridge solved both these issues.
Loads offered were similar to the standard military loads for the .45 ACP, but with fully lead bullets rather than the full metal jacket bullets used for .45 ACP. This was done to reduce barrel wear in the shallow rifled revolvers in which it was to be used.
The round is currently still in production by Corbon in their DPX and Performance Match lines of ammunition and is also manufactured by Georgia Arms and Buffalo Bore Ammunition.
See also
*List of rimmed cartridges
Below is a list of rimmed cartridges (R). Although similar, rimmed cartridges differ from rimfire cartridges (list). A rimmed cartridge is a cartridge with a rim, whose primer is located in the center of the case head; the primer is detonated by ...
References
{{DEFAULTSORT:45 Auto Rim Pistol and rifle cartridges Rimmed cartridges