AR-15 9MM adapter

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  • Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    I have an AR15 (who doesn't anymore right?) and want to look into a 9mm or 40S&W chamber for it. I've seen they make magazine adapters so the lower takes a GLOCK magazine. I assume then all you need is an uppper including a BCG.

    Does anyone have any info or actual experience with this process? I've done 223->300blk and even 458 socom but i'm going all dumb when it comes to 9mm for some reason.

    i'm not looking for a match quality one.. just something that fits the need/desire to pew pew at gongs and paper via 9mm off AR platform.
     

    Gcs7th

    Ultimate Member
    Jan 26, 2012
    1,280
    AGC
    Complete upper and a 9mm buffer are required unless you get a cmmg radial delayed blowback that uses a std carbine buffer. Magazines you can pick your poison. Colt and Glock are the most common with mag well adapters or dedicated lowers an option. Some have LRBHO (last round bolt hold open) others do not. Mean arms makes an insert to convert pmags to 9mm which is pretty cool.
     

    photoracer

    Competition Shooter
    Oct 22, 2010
    3,318
    West Virginia
    Lower will need a mag adapter. Upper you can use the charging handle, receiver, barrel nut, hand-guard, and the carbine buffer spring. Rest has to be replaced meaning barrel, BCG, buffer weight (maybe), and most likely different optics (red dot instead of scope).
    Or you could build a custom upper in 9mm and just add the mag adapter when you want to shoot that.
    Not what I did but it can be done that way on the cheap. Get a decent BCG (Faxon or others) not something off GB. I learned that the hard way breaking 2 of them.
    I have a couple of LW PSA 16" 9mm barrels I no longer use if you want one cheap (plenty accurate). I think one has a JP 9mm muzzle brake on it also.
     

    ironhead7544

    Active Member
    Oct 27, 2018
    188
    For the lower, you will also need a buffer. There is plenty of info on the net about building the AR-9.

    Today, I would say get the Ruger 9mm carbine.
     

    Sirex

    Powered by natural gas
    Oct 30, 2010
    10,380
    Westminster, MD
    Complete upper and a 9mm buffer are required unless you get a cmmg radial delayed blowback that uses a std carbine buffer. Magazines you can pick your poison. Colt and Glock are the most common with mag well adapters or dedicated lowers an option. Some have LRBHO (last round bolt hold open) others do not. Mean arms makes an insert to convert pmags to 9mm which is pretty cool.

    I have been looking at getting a 9mm upper as well. I googled the cmmg radial delayed blowback 9mm, and so far all I have seen are bolt and barrel combos, so I assume I need to find a stripped upper receiver to build an upper, or do you know of anyone who sells the complete cmmg radial delayed blowback upper? My hope was to just swap uppers on one receiver, and have a multi-role and caliber AR, with no mods needed to the lower. I was going to get some of the Mean Arms Pmag adapters. Thanks for any info
     

    MindTheGAP

    Active Member
    Jan 4, 2018
    574
    Maryland
    Lower will need a mag adapter. Upper you can use the charging handle, receiver, barrel nut, hand-guard, and the carbine buffer spring. Rest has to be replaced meaning barrel, BCG, buffer weight (maybe), and most likely different optics (red dot instead of scope).
    Or you could build a custom upper in 9mm and just add the mag adapter when you want to shoot that.
    Not what I did but it can be done that way on the cheap. Get a decent BCG (Faxon or others) not something off GB. I learned that the hard way breaking 2 of them.
    I have a couple of LW PSA 16" 9mm barrels I no longer use if you want one cheap (plenty accurate). I think one has a JP 9mm muzzle brake on it also.

    Serious question - how did you break a 9mm bolt carrier? Unless you're talking CMMG's RDBB BCG, I'd have thought it near impossible. All my 9mm bcg's are basically one piece with the only 'breakable' pieces being the extractor / firing pin.

    No shade, just wondering what happened so I can (potentially) avoid it myself!
     

    MindTheGAP

    Active Member
    Jan 4, 2018
    574
    Maryland
    I have been looking at getting a 9mm upper as well. I googled the cmmg radial delayed blowback 9mm, and so far all I have seen are bolt and barrel combos, so I assume I need to find a stripped upper receiver to build an upper, or do you know of anyone who sells the complete cmmg radial delayed blowback upper? My hope was to just swap uppers on one receiver, and have a multi-role and caliber AR, with no mods needed to the lower. I was going to get some of the Mean Arms Pmag adapters. Thanks for any info

    a) Yes, you'd need an upper for that BCG / barrel combo. No different than an AR-15 at that point except it's sans gas tube / block.

    b) Believe it or not, CMMG sells complete CMMG 9mm RDBB uppers. See bottom of this page for options: https://www.cmmginc.com/9-arc/

    c) IMVHO, the Mean Arms adapters are cool (I bought 3 when they released), but they don't offer LRBHO, and they require gutting one of your AR PMags. I'm sure most of us have dozens of magazines, but just my .02. For better value / overall function, I'd go for a NFA C-9 lower with the LRBHO upper. In theory, you may even be able to use a Gibbz or NFA side-charging upper with the LRBHO and mate that with the barrel / BCG from CMMG to make one slick PCC.
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    thanks all. it's, not as clean cut as switching the upper w/ a dedicated BCG. i dont shoot enough "pistol" and though i might w/ this option.
     

    Sirex

    Powered by natural gas
    Oct 30, 2010
    10,380
    Westminster, MD
    a) Yes, you'd need an upper for that BCG / barrel combo. No different than an AR-15 at that point except it's sans gas tube / block.

    b) Believe it or not, CMMG sells complete CMMG 9mm RDBB uppers. See bottom of this page for options: https://www.cmmginc.com/9-arc/

    c) IMVHO, the Mean Arms adapters are cool (I bought 3 when they released), but they don't offer LRBHO, and they require gutting one of your AR PMags. I'm sure most of us have dozens of magazines, but just my .02. For better value / overall function, I'd go for a NFA C-9 lower with the LRBHO upper. In theory, you may even be able to use a Gibbz or NFA side-charging upper with the LRBHO and mate that with the barrel / BCG from CMMG to make one slick PCC.

    Thank you
     

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