10mm ‘No Moonclips’ Single Action Revolver – Cimarron Badboy – SHOT Show 2020

If you hail from cowboy blood, no gun really feels comfortable in your hand unless it is a single action revolver. This new Badboy from Cimarron brings a modern and very practical cartridge into a gun that would be a preference for many.

The 10mm is a light, fast, and hard hitting caliber developed for the FBI in the 90s. They only adopted it only briefly though, because it is monster. In the Smith & Wesson alloy frame semi-autos of the day, the 10mm made followup shots difficult, and slight shooters couldn’t really mange it at all.

Defensively, the 10mm tends to over-penetrate, regardless of the load, and the whole expedition actually gave rise to the .40 S&W caliber, which is a slightly shorter version of the same cartridge. Eventually the FBI went back to 9mm regardless, despite the disappointment that it had been in the past.

For handgun hunting the 10mm rocks. It is much more manageable than a .44 Mag, and it shoots flatter at longer distances, so the required holdover is less as targets get further away.

Out on a ranch, where a coyote opportunity may be very brief, and where you just don’t need the extra power of a .44 Mag for even large hogs, a 10mm is kind of just perfect.

In a revolver the 10mm can be a problem though, because it has a rimless case, meaning that it does not have a protruding edge at the back. In a magazine, you don’t want those edges because they can stack up on each other. Bun in a revolver, those edges are handy, because they hold the cartridge at the back of the cylinder.

For rimless cases, in a double action revolver, where the cylinder swings out, generally you have to use “moon clips” to hold the cartridges at the back, or the gun has to have some kind of built in retention system.

In a single action, where the cylinder stays in the gun, and you load and extract through a loading gate, none of this is a concern. You just drop the 10mm cartridges in as you would a .44 Mag, .38 Special, or any other rimmed case.

The MSRP on the Cimarron’s 10mm Bad Boy is $726.05 (I don’t know if that extra 5c is a wooden nickel or not), On GunsAmerica the existing .44 Mag Bad Boys are just north of $600.

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  • Ron January 25, 2020, 12:26 pm

    Why get the 10mm when the 44mag is over $100 cheaper. If recoil is a problem you can feed 44 special ammo all day. 44mag version is a much better value.

  • JG January 25, 2020, 10:31 am

    Just ‘nother gimmick…. 357 Mag works just fine in the same power bracket.

  • Brian January 25, 2020, 10:09 am

    “For rimless cases, in a double action revolver, where the cylinder swings out, generally you have to use “moon clips” to hold the cartridges at the back, or the gun has to have some kind of built in retention system.

    In a single action, where the cylinder stays in the gun, and you load and extract through a loading gate, none of this is a concern.”

    I’m wondering why a single action cylinder vs. a double action cylinder has anything to do with proper head spacing of the cartridges, which is what the moon clip is for.

    • Michael September 12, 2020, 9:33 am

      The cylinder on the S&W 610 could be cut to headspace on the mouth of the cartridge (and maybe it is) just like the Ruger Blackhawk chambered in 30 carbine or the Cimarron Bad Boy in 10 MM I don’t know why S&W chose to use moon clips for the 610 and 646 models. I know it’s a lot easier to load six at a time with the full moon clips rather than one at a time.

    • a11four1 November 23, 2022, 8:41 pm

      Few straight walled cartridges head space on the case mouth. It’ll work in an automatic, having suitable extraction, adapted to rimless cartridges. Such mechanization isn’t practical in revolvers.

      Both half or full moon clips are technically dual purpose; facilitate headspace of ammunition and extraction of fired case. At least one cartridge, .45 ACP has a rimmed brother, .45 Auto Rim, literally the ACP case with a rim. It’s prominent, at .090 thickness IIRC.
      That (moon clips) came about with the Colt and Smith & Wesson chambered large frame revolvers in .45 ACP, augmenting troops, with inadequate production of 1911’s. Those revolvers came with moon clips, to use the common cartridge.

      Also IIRC, Auto Rim came about, when massive quantities of revolvers were surplussed to the public, mainly for convenience, not having to keep track of moon clips.

      My Model 25 shoots equally well with carefully prepped ACP cases and moon clips, or normal reloads in Auto Rim. The headspacing of rimmed cartridges is slightly more consistent with less ‘parts’ involved.
      But it’s hard to beat the rapidity of loading with moon clips, full or half. A few half clips in a pocket are MUCH easier to retrieve than full moon.
      So, like everything we enjoy, there are trade-offs.

      Sometime later with ramped up production of 1911’s and requisite ammunition

      • a11four1 November 23, 2022, 8:46 pm

        Ignore that last sentence, it’s an orphan from clarifying comments.
        But recall at least one more moon clip used in revolvers; the Ruger 9mm. I’m not aware of any version or push for a rimmed 9mm Parabellum.

  • Robert Smith January 24, 2020, 9:04 pm

    It would be a no-brainer for Cimarron to include a 40 S&W extra cylinder. Ruger used to sell their 10mm/ 40 SW Blackhawks as combo guns.

    • Michael September 12, 2020, 9:26 am

      Cimarron chose to add the 38-40 win as a optional cylinder instead of the boring 40 S&W

  • gerald clauson January 24, 2020, 3:34 pm

    Jeff Cooper introduced the world to the 10mm in 1983, for the Bren 10 pistol. Not developed for the FBI in the 90s.

  • shrugger January 24, 2020, 3:20 pm

    Wheres the 10mm lever gun?

  • kb31416 January 24, 2020, 10:12 am

    Um, why not just use a 41 magnum if you want a 10 mm in a single action revolver?

    • WVinMN January 24, 2020, 11:00 am

      Ammunition availability.

  • Dusty January 24, 2020, 8:33 am

    This isn’t a new idea. I’ve owned a Blackhawk in 10mm for at least 20 years.

    • Michael September 12, 2020, 9:36 am

      Yes, Buckeye Sports contracted Ruger to make a Blackhawk in 10mm/38-40 back in the late 80’s They did not seem to sell very well then but, now I bet those would be very collectable.

  • Jim Parker January 24, 2020, 4:12 am

    this makes me wonder if 40 caliber S&W would fire from the same cylinder.

    • kb31416 January 24, 2020, 10:11 am

      Short answer: no. This assumes that the round head spaces on the case rim, which is about the only way to do it with a rimless straight walled cartridge.

    • Michael September 12, 2020, 9:23 am

      The 10 mm head space’s from the mouth of the cartridge not like a rimmed case and with the 40 S&W case being shorter, it would fall too deep in the case.

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