Home CMMG CMMG Banshee: The Unique Radial Delayed Blowback System

CMMG Banshee: The Unique Radial Delayed Blowback System

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In 2015, the CMMG company decided to develop a pistol-caliber AR carbine firing .45 ACP. Such things were becoming common in 9mm, but .45 was a more open market opportunity. They spent substantial time trying to perfect a simple blowback system, only to find that the recoil impulse was causing occasional feed failures that just couldn’t be rectified. They next tried using the regular AR “direct impingement” operating mechanism, but that wouldn’t provide enough energy to run the system reliably – and was very direct to boot. Just when the project looked hopeless, they took inspiration form the WWII Reising submachine gun – a delayed blowback .45ACP system.

Thinking about delayed blowback options, they hit upon the idea of using the AR cam pin as an accelerator lever. By cutting the back of the AR bolt lugs at 45 degrees, they created a system where the bolt would try to rotate and unlock under direct pressure from firing. This rotating acted through the cam pin to accelerate the mass of the bolt carrier rearward before the bolt head could start to extract the cartridge case. They named the system radial delayed blowback, and proceeded to spend 2016 perfecting the system, ultimately releasing it in April 2017 to the market. Following that, they expanded their product line from .45 ACP to include 9×19, 5.7×28, .40 S&W, and 10mm Automatic.

There are very few new ideas in firearms operating system these days, and the radial delayed blowback is a clever and elegant one, using an existing set of parts in a novel way.

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41 COMMENTS

  1. I bought a banshee Mk47 and upon field stripping prior to firing I found the firing pin bent horribly out of shape. I took it back to my lgs and they sent it back. 8 weeks later I get it back, take it out and cannot get through a mag without malfunction. I field strip again and find the face of the buffer had been striking the retaining pin repeatedly and beat it all to hell, and i don't even think that had anything to do with it malfunctioning. I again returned to cmmg and now i finally have a banshee that runs OK..most of the time. I feel that CMMG should have replaced it, not repaired it repeatedly. They offered no explanation as to why or how the firing pin was mangled, why it wouldn't feed or would jamb two live rounds together , and the second time I went to return it they were resistant to even take it in for repair, claiming they had already repaired it and had posted a video proving so. Luckily for me, the owner of my lgs had taken the gun home with him to test fire himself after I returned it the second time and found what I said to be true. I have no faith in CMMG or any of their weapons.

  2. CMMG is a stand up company as well. They started with the .22lr conversions and now they give us this. They were very good and communicative with the order process and progress and met their date as to when it would be produced and shipped. By far one of the best PCC out there and their coating leaves nothing to be desired. Everything they make just seems to be quality and to the highest spec. I’m a fan a customer. They didn’t release a half baked product just to let us beta test it.

  3. Seeing new guns on Forgotten Weapons isn't that bad, if I even can say that. It's like seeing Steve eating fresh MREs.

    I actually think the idea "Now I'll be coming back at you with something new,… or old" should be implemented in Forgotten Weapons too!

  4. A guy I work with picked up a Banshee just prior to COVID hitting us hard in AZ. Hoping to get out with him soon so I can try it myself. I bet this thing is a monster in 10mm.

  5. Have had my Mk45 Banshee since late 2017. It's has very soft recoil. A few drawbacks are proprietary recoil tube, and handgaurd attachment adapter. Also delayed blowback slows the cycle rate. To the point you can easily overrun it with a binary system. Wonderful little house gun though.

  6. I wish the reviews of these PCC firearms would not be based on sub 16-inch barreled full autos. I would like this firearm with a collapsible rifle stock and 16 inch, counter bored to 12 inch rifled bore (about the length a pistol cartridge reaches max velocity) , barrel.

  7. No it is not

    The cam track is longer on the AR 15, because it does not allow the bolt to rotate at the upmost front and back position, which would render the whole delayed blowback system, that sort of thing could never happen also on a recoil operated gun

  8. I love this gun! I really don't like pcc's that use glock pistol mags, the angle of them just looks weird. I know that shouldn't matter, it's about how it shoots, but it just looks so much better with the standard ar mags. Just wish I lived in the States so I could own one, or 5 lol

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