CMMG's radial delayed blowback may be a game changer for pistol caliber AR's

Discussion in 'Pistol Caliber Carbines' started by drypowder, Sep 12, 2017.

  1. drypowder

    drypowder Les Deplorables Charter Member

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    https://www.cmmginc.com/shop/rifle-mkg-45-drb2-45-acp/

    CMMG has a .45 ACP PCC with its radial delayed blowback mechanism. The delayed blowback reduces pressure before the bolt moves fully rearward, so they are able to use just a H buffer instead of the very heavy buffers typically needed for proper functioning of a pistol caliber AR. This should result in significantly reduced felt recoil. They also have built in a supposedly reliable LRBHO mechanism, which has been a challenge for Glock mag AR designs.

    If this works well, I'm sure they'll expand into 9mm since the AR-9 market is many times larger than the AR-45 market.
     
    Last edited: Sep 12, 2017
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  2. bigfelipe

    bigfelipe TSA Director Charter Life Member

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    Question is why didn't they start with 9mm? How many 45 PCCs are there out there? I'm gonna guess that they tried and it didn't work on 9mm...
     
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  3. rdinatal

    rdinatal Better late then never...

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    Great question.

    -R
     
  4. drypowder

    drypowder Les Deplorables Charter Member

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    Good question. Could be the lower pressure of .45 ACP was easier to work with. Maybe what they learn from this will allow them to design the bolt for 9mm.

    Edit: CMMG will be releasing this in several calibers over the next several months, so I have to imagine that 9mm will be one of the calibers. Also, they will have complete rifles/pistols, complete uppers, and bolt/carrier/barrel kits. The availability of complete uppers and bolt/carrier/barrel kits suggests that a proprietary CMMG lower is not necessary for proper function, which is appealing for those with existing SBR and pistol lowers.
     
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  5. Chdamn

    Chdamn Dungeon Master Staff Member Benefactor Charter Life Member

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    Probably some of the same reasons the Kriss was originally 45. Primarily the felt recoil of the 45 is far greater than that of the nine so a significant reduction will be readily recognized and far more apparent than in a 9.

    And 9mm in a rifle platform has very little recoil to begin with. And as Joe said, the lower pressure of the 45 makes it easier to work with.
     
    Last edited: Sep 12, 2017
  6. Slacker

    Slacker Liquor and Whores...

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    If Sig can make a gas operated 9mm, anything else seems silly.

    I have a 45ACP Olympic arms AR15 and it uses a standard weight AR15 buffer.
    No H buffer needed or recommended.

    I think CMMG is just recycling old bell bottom jeans.
     
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  7. drypowder

    drypowder Les Deplorables Charter Member

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    In the designs that use a heavy buffer, whether it's the various AR-9's or the Keltec Sub-2k, you can feel that buffer cycling. Much more so than in 5.56.

    I think a big part of the appeal of CMMG's design will be the reduced pressure pushing the carrier and buffer rearward (and thus allowing for lighter cycling mass), which should make for a smoother shooting firearm; as well as a lighter weight firearm - 9mm AR's are deceptively heavy for their typically short-barrel configurations. And if their LRBHO for Glock mags is reliable, that will help seal the deal for a lot of folks. Though CMMG will definitely make you pay a premium for it; but if this design is everything they are promising it to be, it should help drive prices of other AR-9 parts even lower.
     
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  8. drypowder

    drypowder Les Deplorables Charter Member

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    Does Oly arms have a 9mm upper for which they recommend only a carbine buffer?

    What buffer are you using in your AR-9?
     
  9. Slacker

    Slacker Liquor and Whores...

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    My AR9 uses a JP SCS.
    Prior to that I used a Slash 9Q.
    Ditched the heavy buffer & bolt weight and it changed into a different gun.

    Oly arms 9mm upper also uses (used) a standard carbine buffer.

    You should try out a 9mm AR with the bolt weight removed and a SCS buffer.
    Shoots very flat with very little bounce.
     
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  10. Slacker

    Slacker Liquor and Whores...

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    IMG951368.jpg FullSizeR.jpg Couple pics of mine.
    Super fun & very affordable to shoot.
    I'm buying 9mm brass at $19 per k so leaving it on the ground doesn't hurt that bad.
     
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  11. JRHorne

    JRHorne Member

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    As long as they make a 9MM that uses the Colt pattern mags. I wish they'd do a .45 that used grease gun magazines. My biggest "gun" mistake was not ordering 1 or 2 HK USC carbines back in 2011 before they stopped importing them. Buds had them as low as $1,000 or less. At the time, it would have been pretty easy to be a Navy lower and stock, as well as have the barrel shortened to do a complete UMP conversion for around $2,500.
     
  12. Slacker

    Slacker Liquor and Whores...

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    Oh man, that would make a great thread.
    "Biggest gun mistakes"

    Personally, I've no interest in any of those UMP style HK carbines.
    No decent triggers available, limited optic mounting choices, limited aftermarket support etc.

    These days it's all about options and the AR platform cannot be beat, in that regard.
     
  13. JRHorne

    JRHorne Member

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    Agree with you on the limitations of the form factor, but still when you consider the package you could create around a .45 for $3K (with a nice optic) it is appealing between the history, function, and sex appeal.

    [​IMG]
     
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  14. Slacker

    Slacker Liquor and Whores...

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    Until you shoot it and realize it's all show and no go!
    Crappy cheek weld, no mag funnel, narrow recoil pad, lame grip angle, it chews up brass, has a crappy safety, does not allow a grip forward stance and generally reeks of HK snobbery!

    (I jest...but only a little)

    There is a reason you never see them in PCC matches and price isn't it.;)
     
  15. JRHorne

    JRHorne Member

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    Well what do you expect from a 30 year old design and something made by Germans!
     
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  16. Flashpoint

    Flashpoint Member Charter Member

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    Yep, a Sub2k in .40 is not all that fun to shoot due to the heavy buffer mass slamming your shoulder. By contrast shouldering my Roni housing a G22 and 9" barrel (essentially a .40 PCC) is a pussycat due to the delayed action vs the Sub2k's blowback.
     
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  17. drypowder

    drypowder Les Deplorables Charter Member

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    This raises the point that something like the Micro Roni might be the best option, in many respects, for a 9mm SBR.
    • Takes Glock mags
    • FAR less expensive at ~$200 + stamp vs $400 on up for an AR-9 upper + buffer
    • No fiddling/tweaking required to get it to run properly
    • reliable LRBHO
    • folding stock, so very compact
    • soft shooting compared to run-of-the-mill blowback 9mm AR/rifle designs
    Downside is it's ugly as sin compared to all those sexy AR-9's.
     
    Last edited: Sep 13, 2017
  18. bigfelipe

    bigfelipe TSA Director Charter Life Member

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    I don't know. I think they look kinda cool. If I was going to SBR a GLOCK though, I'm just get the Fab Defense stock and foregrip. Much more compact and true to factory design. Cheap too...

    I like the KPOS better than the Roni though. It seems much less bulky...

    [​IMG]
     
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  19. Flashpoint

    Flashpoint Member Charter Member

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    Not as ugly as a sub2k, or high point carbine!
     
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  20. Flashpoint

    Flashpoint Member Charter Member

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    Also the Roni is at least as light as the sub2k if not lighter, and there is no comparison in that department with a 9mm AR. The only real downside I see to my Roni is with the 9" barrel I doubt it would run with a can on it. Good, now I don't have to buy a .40 suppressor. :)
     
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  21. MadMardigan

    MadMardigan Antagonist

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    Also a large aftermarket for Glocks, more or less the AR of handguns
     
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  22. drypowder

    drypowder Les Deplorables Charter Member

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    Yep, a lot of good points re: the Roni, but I can't get past the mental block, irrational as it may be, of SBR'ing a Glock.
     
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  23. MadMardigan

    MadMardigan Antagonist

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    With the brace... I can't see paying the gov 200 dollars to inconvenience me traveling between states.
     
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  24. drypowder

    drypowder Les Deplorables Charter Member

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    Ah yes, of course this would be offered with a brace. $300-$350. Not cheap enough to sway me from an AR-9 pistol. $200 would be a lot more compelling.
     
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  25. MadMardigan

    MadMardigan Antagonist

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    I've thought about the 16" PCC like you posted, if I had a 45 cal can, I'd probably get one.

    I've got a couple guns I want, and couple I might sell.
     
  26. drypowder

    drypowder Les Deplorables Charter Member

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    16" PCC? Me? No way. Now that we have braces (and especially for those who have SBR lowers), 16" barreled PCC's are a niche market, IMHO. I would have zero interest in one.

    If you're referring to the link in the OP, that's just what they rolled out first. I'm sure there will be shorter uppers and bolt/carrier/short barrel kits in various calibers. Something a lot shorter than 16" would be much more suitable for a can.
     
    Last edited: Sep 13, 2017
  27. Short Fuse

    Short Fuse He yall watch this.... Charter Member

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    Olympic is out of business. You would have to scrape up a old one.
     
  28. BigWaylon

    BigWaylon Head philatelist Staff Member Charter Member Benefactor

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