HGR 053 - Auto-Caliber Revolvers & Moon Clips

Hello and welcome to Handgun Radio! I’m your host Ryan Michad from the wilds of Central Maine, and this is your home for all the news, information and discussion in the handgunning world. This week, Matt and I discuss the world of moon-clips and auto caliber revolvers, used both for self-defense, plinking & competition. There’s a whole world of revolvers out there chambered for automatic pistol cartridges!

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Week in Review:


  • Did some reloading. Components seem to be showing up much more frequently around here, which is great!
  • Looking to do some more interviews coming up. I’d love to get in touch with the folks from North American Arms and discuss their fine Mini-Revolvers, as well as Bill Wilson to discuss his 1911 work and his new venture into custom Beretta 92 components. Stay tuned!


*shot a few idpa matches, finally got back to shooting my wheel guns. way more

            fun. Signed up for Ky Kolonel IDPA match in oct.

       *    went back to the 18th century, shot flintlock Ky rifles for a few days. Great to get

             away from electronics for a bit.


Main Topic - Auto-Caliber Revolvers & Moon-Clips

We all know the typical revolver cartridges; .38 Special, .357 Magnum, .44 Special & Magnum, .45 Colt and the rest, but revolvers can be chambered in auto-pistol cartridges too! Back in World War I, the United States entered the conflict, but realized they did not have enough 1911 .45 Automatic pistols to supply the troops. An employee at S&W devised a way to chamber their large 1917 revolver in .45 ACP by using two, stamped sheet steel 3-round moon clips to function as the rims of the rounds. This facilitated proper headspacing and proper ejection of the rounds. Another advantage was the quick loading procedure facilitated by dropping in two moon clips of three rounds each; much faster than loading rounds individually. Colt manufactured a similar gun as the S&W to supply the military with, and the rest is history. Since that time, there have been a plethora of revolvers chambered in automatic pistol cartridges, some more successful than others. We will be discussing some of the advantages & disadvantages, from both a competition & defensive use standpoint. We will also talk about some of the cartridges and guns that were introduced that used the moon-clip system.



  • Fast reload time
  • Short stubby cartridges load quicker & easier in a revolver.
  • Moonclips keep all rounds together and go in the gun as one unit.
  • No manipulation of knobs or buttons like with a speedloader.


  • Moonclips are not the most durable; a bent moonclip can tie up your gun.
  • The guns will sometimes not function well without a moonclip. Headspace issues can arise.

Calibers & Guns:

S&W 625 (.45 ACP): Produced from 1988 to present. A stainless steel revolver

chambered in .45 ACP and .45 Auto-Rim. Used frequently for competition.

S&W 610 (N Frame 10MM): Produced in the heyday of the 10 MM auto round, the S&W

Model 610 was only produced from 1990 to 1992. Had the added advantage of being able

to fire .40 S&W much like .38 Spl shoots in a .357 Magnum.

S&W 646 (L Frame .40 S&W): Originally produced as a Performance Center Model, the

646 was made into a limited run production model in 2000. Only about 300 of the PC

Models were made. Production ceased in 2003.

S&W 547 ( K Frame 9mm w/out use of clips): A fairly rare K-Frame 9mm revolver. It

did not use traditional moon clips, but used small extractor claws that engaged the

ejector groove on the rimless 9mm case. Problems arose with stuck cases since the

claw would not always reliably grab the round.

 S&W 940 (j frame 9mm): Produced from 1993 to 1996, the 940 was your

standard J-Frame chambered in 9mm Para. The Michigan State Police issued them as

backup guns but found the officers were using the moon clips as screwdrivers, bending

the clips which could lock the gun up. The 940 quietly faded from production in 1996.

Ruger SP101 & Security Six (9mm): Ruger’s fantastic small and medium framed

were chambered in 9mm as well for quite some time. Ruger made their own proprietary

moon clips for their guns. The SP-101 is no longer listed in 9mm.

Oddball Chamberings:

9mm Federal (Rimmed 9mm Case): Simply a duplicate of the Federal 9BP round, a

standard pressure 115 grain 9mm JHP at 1100 fps. It is simply a rimmed 9mm round.

.45 Auto-Rim: In an attempt to negate the moon clips, Peters cartridge originally came

up with the .45 Auto-Rim, which is essentially a .45 ACP with a rim. It is produced in

limited numbers today.

New Segment: Obscure Gun We Want

This is a new segment where we pick and link to an obscure gun that we want. This is purely a “if money were no object” exercise, and maybe you (the listeners) will hear about a gun you didn’t know existed and want to buy one too!!!

Ryan: I want a .44 Special Snub Nose revolver with an unfluted cylinder on the L-Frame. Thank you Smith & Wesson!

Matt: Singer 1911. Id like my dads he used in  Korea. He thought it was funny as hell his gun was made by a sewing machine company. Priceless to me but worth thousands to others! 


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Until Next week, Have fun and SAFE SHOOTING!!!!