CMMG Banshee at the Range

Yesterday we looked at the novel Radial Delayed Blowback system invented by CMMG for their 9mm AR carbines; today we are taking it out to the range to try. It does indeed do exactly as advertised – even in a lighter platform like this SBR, the recoil impulse is significantly less than in simple blowback 9mm ARs. Very cool to see innovation still existing in a marketplace that has been so heavily optimized!

51 Comments

  1. Brilliant adaptation of the Thompson Autorifle / VP concept to the AR platform, with a better understanding of balancing the relative masses of the bolt components (and a more appropriate cartridge).

    Strange – I saw Part One on YouTube yesterday because I happened to be on YouTube (which apparently knows what I like), but it wasn’t and still isn’t on this site.

      • Villar-Perosa, which also forced the bolt head to cam the rear bolt / bolt carrier open against a mechanical disadvantage – but, being built in apparent ignorance of the principles of delayed blowback, put most of the mass into the forward bolt.

  2. Hasn’t CMMG closed their doors? It would be nice if this system was profitable, but it looks like the barrel extension needs to be changed as well.

  3. Their website not only looks operational, but also has a popup that seemingly refers to today’s market conditions.

    I’m not sure I understand the issue you’re raising in your second sentence. AR barrels are generally sold with extensions installed. Nearly all non-CMMG pistol caliber barrels have no lugs because they’re made for blowbacks, so a CMMG build or conversion would require a CMMG barrel whether the extension is proprietary or not. BCG / barrel combos are $349-399.

      • Patent says so… At firing, empty case with high pressure inside, first forces the angled lugs to rotate then, cam pin receives motion as trying to transmit to the bolt carrier with a disadvantaged leverage as most of gained momentum being wasted for this job and thereby leaving less momentum to rotating bolt causing to slow its rearward push as causing less friction on contact surfaces at lugs and counter recesses all resulting a soft recoiled bolt and carrier for even more powefull rounds than 9 mm…

        Needs near perfect machining and parts control… Seems not suitable for rifle size rounds… IMHO…

        • Might work with intermediate calibres though

          For rifle size rounds, the lugs would have to be at a steeper angle, less amount of lugs (4 or 3) with more rotation of the bolt to delay extraction. The Johnson Model 1936 prototype used a delayed blowback operation that worked reliably but not sure what type of delay it used.

          As for the radial delay blowback operation, wonder if CMMG would make an AR18 derived platform using it.

      • You could perhaps run a further spring; running from the unused gas key over the barrel, add more resistance… Squish it against a mount added to the trunnion via a squisher at the front of said springs guide rod extension, mounted to the gas key; not much room for much more mass.

        Sproing! Like that. No? Kinda think 5.56mm needs more resistance, unless it is just me.

        Nice system “the cmmg one” someone mentioned wear and tear I think in the other vids comments; might come into play, although it may not be such an issue in pistol calibres.

          • Cut grove for hammer, more also to allow for said added rotation; probably should have thought this through.

          • Might work; main spring is seperate, carrier just turns against it… Possibly other problems, he he.

            Anyway, just a thought.

          • Few more beers, rotating a pen… Reinforce, said ledge. Burp. Whos got a dremmel and a spare gun.

          • Bats spend alot of time upside down: So they have a upside down coagulation system probably, that the virus latched onto in us. Who’s got a hammer, he he.

          • Work that in 5.56mm \ ledge, bump. Meh, metal files. Write down the correct bump. Can’t reproduce it, stupid machinist.

            Siberia, see you’ve improved. Germans are over there killing everyone any chance like.

          • Lose the forward assist… Mount the ejection cover above, to facilitate said “bulky ledge” bang! Aye. Works… Just about.

          • The “bump” would mean to rotate, it would need to rotate the whole mass of the bolt/friction etc towards the cam stud; so in theory more delay, I understand your larger surface area twist delay idea… I think; because I have long thought the Johnson bump, was one of the reasons why they used a multiple short surface area lugs “turning” I.e. Said wee bump would be enough to rotate it; unlike with fewer wider surface area lugs.

          • Reckon the cam track alteration would be sort of a half / but more – angle; point being, facilitate carrier moving into cam stud, but on return allowing it to rotate clearly. Needs doodling. Hammer cut out left side facilitates said rotation movement of carrier into the cam stud; as above.

          • To rotate the entire bolts mass anti-clockwise even by say 1cm; including friction all round, may delay more than a bit more surface area on the lugs… Perhaps it needs both in 5.56mm; still reckon it may work, more or less sober.

          • The bolt going forward will impart momementum; if the angle is right, with said impetus… It will turn. Should. Oil. He he.

            Anyway, think that was worthwile end of mini verbal splurge; as oppose diatribe.

          • Cut a wee wedge; / knock cocking handle > that way, on forward travel. Ways, probably… He he. Seperate cocking handle: handle was stud in johnson; was it, forgot… Meh, easy enough to find out have fun.

        • The stud/handle being seperate now isn’t relevant… Meh Larium “you guys” want to watch taking that covid 19 (cure) zinc ionphone etc, watch the cure isn’t worse than the illness… Not that Malaria isn’t bad; but lariam can totally make you mental for a decade, long time.

          • I know it isn’t Lariam Trump and the Tanzanian president who sent a paw paw “fruit for testing” which came back positive for the virus… A paw paw… In Tanzania; but that dystopian future of a paw paw talking to Donald and the Tanzania guy in charge of the world, is not impossible via Malaria meds; don’t even have to take that much either.

            10 years of a paw paw talking to Donald.

          • He doesn’t drink; but if you do… Watch out for that, sat in your liver; you’ll think you have problems.

            Slight liver “thing” BANG!!! Glad theres no guns here, fact; paw paw, said it (would have an all)

      • Maybe use your fewer/greater surface area lugs in conjunction with the above; bet there is away, as in 5.56mm it won’t be too far away already probably from working “reckon it is a bit away” but be worth trying… Radial thing works basically as per, and while no gas might not prove to be better; maybe it would at least work enough to prove gas is better, think it has potentional anyway.

  4. Stupid question: Does this system have a potential future in law-enforcement, or will it be dismissed as a “pampered poodle” intended for rich guys at the range?

    • Cherndog, why would the police go back to pistol caliber carbines when they’re packing AR carbines now?

      • Not being bound by the NFA, an urban department may find a PCC / SMG an acceptable tradeoff vs. 400m range. Out of an 8″ barrel 10mm offers KE equal to 5.56, probably dumps more in the target (more frontal area, JHPs designed for that velocity envelope), and doesn’t detonate half its powder in front of your face.

        • Very big reason that some departments went back to the MP5 for some uses is, that as Mike says, 556 from a short barrel sucks. especially when shooting inside a house and blinds and deafens you and everybody else in the room. Making efficient team communication impossible. In Europe mostly MP5 still for entry teams for these reasons with a few shorty 556 mixed in.

          Also you can shoot the same ammuniiton in pistol and SMG making supply easier for the police department.

  5. Please do not insult the Poodles. These are great working hunting dogs. Even dwarf ones.

    But it’s rather something like a Pekingese. Very nice and loyal.
    But suitable only for a sofa. LOL

  6. We’ve been using the cmmg radial delayed uppers for awhile now, with excellent results. Combined with the pmag adapters, you can’t really find a better 9mm system for the cost. It’s also safe for use on transferable m16 lowers since the fcg pins don’t take a beating. We have one on a post sample lower with over 7000 rounds, mostly full auto. They run like a champ.

    If you really want to have fun with it you can use an A5 receiver extension, tubbs flat wire spring, and kynshot 9mm hydraulic buffer. It brings the cyclic rate down to around 550 rounds per minute.

  7. “…It brings the cyclic rate down to around 550 rounds per minute…”(C)

    I don’t understand something.
    And what is the rate of fire without all the extras?
    Whether You like it or not, it will inevitably be compared with the “regular” 9mm M16.
    And, for example to me, it’s not yet clear what is better, than twice the price?..
    Just, another 9mm M16 for the mags from Glocks?

    • If you run it with a normal carbine spring and buffer it’s around 800-850 rpm on full auto depending on the ammo.

      The whole point of the system is that the recoil is MUCH lower than a straight blowback. You don’t need ultra heavy buffers, and you don’t put excessive wear on the fcg pins that will eventually egg out the holes in your lower receiver. The radially delayed setup is also much more tolerant of being suppressed.

      • “normal carbine spring and buffer it’s around 800-850 rpm on full auto depending on the ammo”(С)

        This is incomprehensible.
        How much does a carrier assy without buffer, 14oz?
        The Colt SMG is about same.
        At the same time, the rate of fire is about the same …
        And about the same rate of fire is the MP5, with a weight of the movable assembly of about 7.5oz.
        A pure IMHO, but if there is a blowback-delay, then it is insignificant and does not affect anything.

        Recoil…
        With a 9mm cartridge, gun weighing 4.6 pounds, as well as a muzzle brake and a butt stock…
        I think that after installation, the scope and suppressor, each weighing half a pound, the recoil will completely disappear. 😉

        Rear report …
        It seemed to me that, after the couple first shots, the operator ran away to the back side of the ejection port and never returned.
        I wonder why?.. 😉
        If the rate of fire is the same as that of the Colt SMG, then the time for opening the chambers is the same.
        So the rear exhaust will be the same.
        And those who shot from the Colt SMG with the suppressor are aware of the size of this pleasure.

        I could be wrong? 😉

        • You can theorize all you want, but in reality there is an enormous difference between the two. A colt 9mm upper requires a super heavy buffer, whereas the cmmg can run at a similar cyclic rate with a normal carbine buffer. Keep in mind that the radial delayed action is keeping the chamber closed longer, while the colt (or similar direct blowback 9mm) opens much faster.

          The difference becomes especially apparent when shooting full auto. The cmmg is easy to control and keep on target, and the recoil is substantially lighter. Direct blowback 9mm uppers have quite heavy recoil because of the bolt mass and heavy buffer, plus nothing to slow down the unlocking.

          • OK. Let there be a bickering.

            Let’s start with the weight.
            Early pistols had a buffer weighing 3,96 oz. and BCG-1,78 oz. They worked unstably and demanded about 500 shots for “run-in”. By the way, a good branch. Perhaps not the best branch of all, but it has numbers. https://forums.brianenos.com/topic/258538-cmmg-guard-tuning-9mm/
            In the future, the transition to a heavier buffer of 5,36 oz. https://cmmginc.com/faq/
            And, apparently, a heavier BCG, 11,8+3,4=15,2 oz.(?) https://cmmginc.com/product/action-tuning-kit-mkg/
            This is even a little more than Colt SMG, 14,3-14,5 oz. (With a Colt buffer weight of about 5,4-5,5 oz.)
            The rate of fire also roughly corresponds to about 800-900 rpm for both.
            Since the characteristics of the hydraulic buffers are unknown, I see no reason to compare them. Although when using them, the rate of fire is reduced by close values.
            Only I alone do not see a decrease in the weight of the moving group or rate of fire?

            Yes. Can anyone tell me the weight of the BСG MP5 and MP5K? I think for MP5 7.5-8 oz.?

            Now, if You don’t mind, let’s look at the back report. This is how it looks on the SMG with a delay. https://youtu.be/SPjliwcbKFg?t=551 watch from 9,10
            and https://youtu.be/GHBZTBOke1s?t=115 watch from 11,54
            And here is what it looks like https://youtu.be/bIqaHcNKhRs?t=300 watch from 5,00
            or https://youtu.be/wnmfdKXn0eM?t=187 watch from 3,07.
            Only I alone see the difference?

            We pass to the toss, recoil and controllability.
            I wonder how it is rated? Like “that guy said it was cool”? 😉
            In fact, for this purpose, mankind has come up with some devices.
            For example https://ransomrest.com/the-master-series-rest/
            Since many guys manage to not always notice the difference between 12,7 and 7,62 😉
            (This is not a stone on Ian’s backyard. Althoug…)

            Where could I be wrong?

            In short, there are sometimes adults and sane people. So there’s nothing to treat us.
            Or just someone from childhood dreamed of becoming a doctor? LOL

          • I do not need to theorize.
            I was developing this system about 12-14 years ago. And after all the calculations and reflections, I came to the conclusion that with a gear ratio sufficient for the effective operation of the delay, the service life of the bolt will sharply decrease. M16 bolts, even with much lower loads caused by overgas, “love” to split the back. And with a safe, full-time relationship, this does not make sense. Therefore, the project was abandoned.
            https://www.thetruthaboutguns.com/ar-15-bolt-carrier-group-bcg-how-it-works-maintenance-and-how-to-buy/

          • OK. Let there be a bickering.

            Let’s start with the weight.
            Early pistols had a buffer weighing 3,96 oz. and BCG-1,78 oz. They worked unstably and demanded about 500 shots for “run-in”. By the way, a good branch. Perhaps not the best branch of all, but it has numbers. https://forums.brianenos.com/topic/258538-cmmg-guard-tuning-9mm/
            In the future, the transition to a heavier buffer of 5,36 oz. https://cmmginc.com/faq/
            And, apparently, a heavier BCG, 11,8+3,4=15,2 oz.(?) https://cmmginc.com/product/action-tuning-kit-mkg/
            This is even a little more than Colt SMG, 14,3-14,5 oz. (With a Colt buffer weight of about 5,4-5,5 oz.)
            The rate of fire also roughly corresponds to about 800-900 rpm for both.
            Since the characteristics of the hydraulic buffers are unknown, I see no reason to compare them. Although when using them, the rate of fire is reduced by close values.
            Only I alone do not see a decrease in the weight of the moving group or rate of fire?

          • Yes. Can anyone tell me the weight of the BСG MP5 and MP5K? I think for MP5 7.5-8 oz.?

            Now, if You don’t mind, let’s look at the back report. This is how it looks on the SMG with a delay. https://youtu.be/SPjliwcbKFg?t=551 watch from 9,10
            and https://youtu.be/GHBZTBOke1s?t=115 watch from 11,54
            And here is what it looks like https://youtu.be/bIqaHcNKhRs?t=300 watch from 5,00
            or https://youtu.be/wnmfdKXn0eM?t=187 watch from 3,07.
            Only I alone see the difference?

          • We pass to the toss, recoil and controllability.
            I wonder how it is rated? Like “that guy said it was cool”? 😉
            In fact, for this purpose, mankind has come up with some devices.
            For example https://ransomrest.com/the-master-series-rest/
            Since many guys manage to not always notice the difference between 12,7 and 7,62 😉
            (This is not a stone on Ian’s backyard. Althoug…)

            Where could I be wrong?

            But perhaps the project was dug out of the bin. And sold to someone who understands this even less.

            In short, there are sometimes adults and sane people. So there’s nothing to treat us.
            Or just someone from childhood dreamed of becoming a doctor? LOL

  8. Reising similarity needs bolt carrier inertia through cam pin as forcing the bolt on hesitation of unlocking at instant of firing. Patent seems no correlation on this manner however… Or at least to my understanding…

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