The .45 Auto Rim

By Wiley Clapp (RSS)

July 01, 2010

I am endlessly fascinated with the .45 Auto Rim cartridge developed by the Peters Cartridge Co. during the 1920s. The cartridge was designed to be used in.45 ACP revolvers made during World War I.


To work with rimless ACP pistol ammo, Colt and Smith & Wesson wheelguns needed a sheet steel clip to hold a trio of rounds with the correct headspace in the gun. The Auto Rim has an extra thick rim that equals the thickness of the clip with the ACP rim, so they work like regular rimmed revolver rounds.


Before World War II, the round was loaded by all of the major companies, but over the years has fallen into disuse. Black Hills now offers a 255-grain LSWC that works well in the old guns as well as the many variations of the S&W Model 25 revolver.


 


Tags:  .45 auto rim,  blogs,  smith & wesson model 25 revolver,  the .45 auto rim,  wiley clapp

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3 Responses to The .45 Auto Rim

Joe the Redneck wrote:
July 22, 2012

Most 45 ACP loads are much too hot for the Web. The 455 has a much lower pressure level. Better to load down to 455 levels.

Richard W Hughes wrote:
September 15, 2010

For years, a Webley MKVI converted to .45ACP was my house gun for the wife and daughters. I kept it stoked with Auto rims, and ACP/moon clips for reloads. Powerful, easy to operate, fast to reload, and easily as accurate as any of my Smiths. There were some potent loads in an old Speer manual I still have. If you are interested, I'll get them out. Otherwise, anything you would load in an ACP will do, as the internal case dimensions are the same.(And you don't have to deal with the exposed case base of the 1911, so the AR can be loaded heavier.)

Gene wrote:
July 07, 2010

How about some reloading information for the auto rim