9mm AR

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  • rbird7282

    Ultimate Member
    MDS Supporter
    Dec 6, 2012
    18,531
    Columbia
    So now I've got the bug to build a 9mm PCC. I've built several AR's and taken the SOTAR Armorer's Course but don't know much about building the 9mm platform so I figured I'd turn to those who've built them here.
    I was thinking of using a Stern Defense magwell adapter for Glock mags so that I can use my existing SBR'ed lower. (Don't really want to get another stamp)
    Anyone have experience with these or are they a piece of crap?
    Or should I just buy a dedicated 9mm lower and throw a 16" barrel (or 14.5" pinned and welded) on it and be done.

    Was going to go with a 12.5" barrel.
    I know about getting a ramped bolt so I think I'm good there.
    I've read about heavy buffers, etc. but would like a little guidance on where to start.
    I'd rather build than buy for this so any advice would be appreciated.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    So now I've got the bug to build a 9mm PCC. I've built several AR's and taken the SOTAR Armorer's Course but don't know much about building the 9mm platform so I figured I'd turn to those who've built them here.
    I was thinking of using a Stern Defense magwell adapter for Glock mags so that I can use my existing SBR'ed lower. (Don't really want to get another stamp)
    Anyone have experience with these or are they a piece of crap?
    Or should I just buy a dedicated 9mm lower and throw a 16" barrel (or 14.5" pinned and welded) on it and be done.

    Was going to go with a 12.5" barrel.
    I know about getting a ramped bolt so I think I'm good there.
    I've read about heavy buffers, etc. but would like a little guidance on where to start.
    I'd rather build than buy for this so any advice would be appreciated.
    Consider the CMMG radial delayed blowback system. I love PCC’s and this is the best 9mm AR platform there is, IMO
     

    DutchV

    Ultimate Member
    Jul 8, 2012
    4,702
    If you aren't wedded to the AR platform, I'd grab a Ruger PC Carbine for about half the price. Wish that had been an option when I built mine.
     

    Ammo Jon

    Ultimate Member
    Mar 3, 2008
    20,774
    KV with 40rd Glock mag?
     

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    rouchna

    Defund the ATF
    MDS Supporter
    Nov 25, 2009
    5,951
    Virginia
    Consider the CMMG radial delayed blowback system. I love PCC’s and this is the best 9mm AR platform there is, IMO

    I would go with this. If not, I would build one using the QC10 lowers. Here is mine (on the right)
     

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    rbird7282

    Ultimate Member
    MDS Supporter
    Dec 6, 2012
    18,531
    Columbia
    If you aren't wedded to the AR platform, I'd grab a Ruger PC Carbine for about half the price. Wish that had been an option when I built mine.



    I’ve seen them but they’re sort of fugly. I’ve thought about it though. I could get one for less than a CMMG delayed blowback complete upper.
    The CMMG stuff looks great but it’s pricey


    Sent from my iPhone using Tapatalk
     
    I have built an AR 9 with Glock mags (dedicated lower, no mag well adapter) and I have a Ruger PCC with the Glock insert installed. Because of the way the rounds in the mag are seated on an angle the round in my AR9 has to literally jump about .40 inches from the front of the mag to the chamber. If you build one I highly recommend installing one of these to ensure it feeds reliably.

    https://palmettostatearmory.com/tac...-for-glock-style-9mm-lower-receivers-163.html
     

    babalou

    Ultimate Member
    MDS Supporter
    Aug 12, 2013
    16,016
    Glenelg
    my bud Outrider58 has one with a lower that takes HK mags. Awesome PCC 9MM he has. He said HK mags muy bueno
     

    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    If you want to use the same AR-15 lower buy some Endomags from Mean Arms, pop over to a free state for standard capacity magazines and install the Endomags into them. No magwell adapter or dedicated lower necessary.
     

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    jimbobborg

    Oddball caliber fan
    Aug 2, 2010
    17,112
    Northern Virginia
    I have yet to see a cheap 9mm AR that is as reliable as my Ruger PCC. After my first AR 9 stopped working properly (at 2000 rounds), I got another inexpensive AR 9. Still not 98% reliable. If I had spent the money that I wasted on these two on getting one JP, I'd be miles ahead of where I am now.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I’ve seen them but they’re sort of fugly. I’ve thought about it though. I could get one for less than a CMMG delayed blowback complete upper.
    The CMMG stuff looks great but it’s pricey


    Sent from my iPhone using Tapatalk

    Barrel/BCG is $375. Build the rest.
     

    rbird7282

    Ultimate Member
    MDS Supporter
    Dec 6, 2012
    18,531
    Columbia
    If you want to use the same AR-15 lower buy some Endomags from Mean Arms, pop over to a free state for standard capacity magazines and install the Endomags into them. No magwell adapter or dedicated lower necessary.



    Are these reliable? I know that CMMG had conversion kits for Pmags and they look similar to these. I’m just curious about reliability.


    Sent from my iPhone using Tapatalk
     

    RuralRifleGuy

    Active Member
    Aug 16, 2018
    918
    Queenstown
    Are these reliable? I know that CMMG had conversion kits for Pmags and they look similar to these. I’m just curious about reliability.


    Sent from my iPhone using Tapatalk

    I haven't had a chance to get mine to the range, but there are a couple of other threads about them here where they sound reliable. That was enough for me to give them a try over a $180+ magwell adapter. CMMG has a partnership with Mean Arms for their ARC mag products.
     

    GuitarmanNick

    Ultimate Member
    Jan 9, 2017
    2,221
    Laurel
    I put a pistol together using a Polymer80 lower, a 10.5" upper assembly, and EndoMags. It runs perfectly but you need to spend a little time "breaking-in" the EndoMags to insure reliability.

    It is a hoot to shoot and surprisingly accurate.
     

    Gcs7th

    Ultimate Member
    Jan 26, 2012
    1,280
    AGC
    I bought a guard barrel/bolt combo and have had a few weird extraction issues. I need to take some high speed video to see if the 9mm case deflector I installed is contributing. Overall it’s a much softer shooter than a direct blowback PCC.
     

    Neutron

    Ultimate Member
    MDS Supporter
    Nov 20, 2014
    1,531
    severna park
    I bought a 9mm upper from PSA and one of those mag well adaptors from them too. Once I figured out that I needed to put a set screw through the front of the mag well to secure the adaptor, all has been good. I think that the reason they quit selling the mag well adaptor is that it would slip a bit and the gun would become unreliable. Unfortunatly most users would not have the ability or desire to drill and tap the mag well to make this product work. Heavy buffer and AR 10 buffer spring help too. I got hundreds of rounds (not thousands yet) and so far so good.
     

    pp55ftw

    Member
    Jan 8, 2019
    62
    Foxtrot Mike products has a dedicated 9mm lower that takes glock mags, I think they are cheaper than a stern defense. Also consider the 9mm AR pistol route.
     

    cstone

    Active Member
    Dec 12, 2018
    842
    Baltimore, MD
    I have one PSA small Glock mag lower that I haven't built yet and two QC10 small Glock mag lowers; one with a .40 S&W upper and the other with a .357 SIG upper. Never had a problem with them feeding from standard G22 mags but it did take some time finding a heavier buffer to get the timing right for the .357 SIG. Both uppers are 16" barrels and I had to wait for QC10 to do a run of these barrels in .357 SIG.

    I also have a Kel Tec Sub 2000 chambered in .40 S&W. Again, a heavier buffer smoothed out cycling in this carbine as well.

    They are fun carbines, much like having a lever gun in the same caliber as a revolver.
     

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