What is 45AutoRim or 45AR

The .45 AutoRim is a cartridge lucky to be in existence. Due to the lack of 1911’s as America prepared to enter WWI, Smith & Wesson and Colt produced revolvers chambered for the .45ACP. These new revolvers were designated as the 1917 by the Army. Even though the 1917 revolver was derived out of what some say is necessity and others say unpreparedness for the war, it is clear the .45AutoRim was an afterthought, and yet it still remains in existence today. It is possibly the least known and least popular revolver cartridges still sold and produced by many ammunition manufacturers. Everything about this cartridge breaks the rules of ammunition development. Revolvers typically introduce new cartridges or are adapted and retrofitted to existing cartridges. It is not ironic however that I can often be found on the range when shooting pistols to always be accompanied by a Smith & Wesson model 625 and a box or two of .45 AutoRim ammunition. I find it very versatile, fun to shoot, easy to reload and I never ever lose a piece of brass which is one of the attributes that make it a “Great Survivor”.


45AutoRim The Afterthought

The afterthought of the 45 AutoRim is evident in that it was introduced a half a decade after the 1917 revolvers by Peters Cartridge Company. Peters developed this cartridge to fire in revolvers without clips, yes clips. Originally “half moon clips” were developed which allows the rimless 45ACP to be easily extracted from a revolver, it also is very important in providing the proper headspace to ensure reliability. During the war the ammunition was prepackaged in these moonclips for ease of use and carry. Eventually it would be the difficulty of utilizing these half moon clips that would drive the Peters Cartridge Company to develop the rimmed version of the .45ACP rimless cartridge (45 AutoRim) in hopes of eliminating these pesky half moon clips. Many decades later full moon clips were developed enabling faster reloads, yet they still proved difficult to load and unload for reuse without the proper tool. There are a number of tools produced to make loading and unloading the moon clips easier. As an old timer I still prefer one of the earlier tools for unloading which simply looks like a hollowed steel pipe and sold by Brownells as a moonclip stripper. Some complain the metal moonclips are difficult to load thus moonclip loaders were produced. Any Internet search for “moonclip tools” will no doubt turn up a vast number of devices to fit your needs. For many years I utilized these moonclips loading and unloading without any tools at all. All of these items come in very handy when competing in club matches.


45AutoRim The Heavy Weight

Reloading the .45AutoRim is no different from any other rimmed revolver cartridge. You will need the appropriate shell holder and I prefer the Redding #17 part number RED11017. Though the cartridge is reloaded the same, there are a few differences from the 45ACP other than its rim. Due to bullet profile and the function of the semi auto pistol, the 45ACP is typically loaded with 230gr FMJ ammunition. Originally this produced the greatest reliability. With better technology in both bullets and pistol manufacturing many hollow points/self defense rounds can be used and be just as reliable as the old 230gr round nose workhorse. In reloading manuals for 45ACP you will most likely find loads that only go as heavy as 230grains; in the .45AR you can find loads suitable for 250grains. Ammunition manufacturers like Buffalo Bore produce ammunition upwards of 255gr, but I would refrain from using these in any of the older 1917 revolvers.

Revolvers chambered in .45 AutoRim usually possess uncommon accuracy. Something I’ve discovered over the years of shooting .45Auto revolvers are the differences in accuracy of the round nose profiled bullet compared to the Keith style lead SWC profile. Most of the jacketed hollow points I have used have performed as well as the LSWC. The long chambers of the revolvers would possibly allow the round nose profile of the 230gr bullet to tilt as it entered the barrel. Couple this with the 230gr short bearing surface and you get rounds that aren’t as accurate.


S&W 625 45ACP Revolvers

The 1917, the 1950, and the 1955 .45cal revolvers are long gone from the Smith & Wesson catalog, but the .45 ACP/.45 AR revolver is a concept that will not die, making the 45AutoRim A Great Survivor. With the introduction of the Classic series by Smith & Wesson the 1917 and model 25 have enjoyed a come back.

The Smith and Wesson .45ACP/.45AR revolver has been designed in many different styles to fulfill many roles: self defense, conceal & carry, competition action shooting and the .45AR with a 250gr bullet extends this revolver into the hunting realm.

The .45 Auto Rim is still a viable fun cartridge which occupies a space between the 357magnum and 44magnum. It combines power and accuracy with very manageable recoil when one wants to avoid the blast percussion of the magnums and is why I can always be seen finishing out a range session with the pure joy of  ringing some steal with 45AutoRim the “Great Survivor”

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Have LOOONG been a fan of the 45 Auto Rim. GREAT cartridge. Shoots beautifully from my S&W 625 (vintage 2002 production). We like the cartridge so much that we carefully file-cut the upper rear cylinder-window of my brother’s stainless Taurus Tracker 45 ACP so that it would work with 45AR. Extremely versatile cartridge that hits like a freight train at modest chamber pressures using lead cast bullets. Eric of Hollow Point molds .com hollow-pointed a 2 cavity Lee 452-228-2R for us to cast a 210 gr RN-LHP that is pure devastation at 1000 fps from the S&W 625 / Taurus… Read more »


Oh my I just got some 45 Auto Rim shells just bought a hundred. Thanks for posting this love my S&W 625 had it for at least 10 years was using the RIMZ moon clips for the ACP the AR are the way to go 👍🏼

Buchanan Precision
Buchanan Precision

Great Post for a great cartridge. Always wanted a M25 or 625 since I already load .45 ACP. Changing the shell plate on a Dillon 550 B for the auto rim cartridge is about a 2 minute operation, and then they can be loaded just like the ACP’s.. Something about those short stubby cartridges with a 250 gr SWC that just looks too cool. It’s on my short list of guns to get before I kick.