Suppressed 9mm AR is loud, what to do?

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  • AssMan

    Meh...
    MDS Supporter
    Jan 27, 2011
    16,211
    Somewhere on the James River, VA
    To begin, I think the thing is hearing safe, but just barely...I'm thinking that most of the noise is coming from the ejection port. Is this ridiculous? My thinking is that a slightly heavier buffer might help here.

    Specs:
    CMMG Colt pattern receiver
    CMMG bolt/carrier
    5" LMT barrel
    H3 buffer (I think)
    Running a Gemtech MultiMount

    I did not try adding an ablative, which I'm certain would help some. Does anyone think that using a heavier buffer would help? If so, what do you recommend?

    Thanks! :D

    edit: I ran 158gr AE subs.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Ejection port bark is common in suppressed AR's. They will never be as quiet as an MP5 because the MP5 has a delayed blowback system (roller locks). The best course of action to reduce this is get the heaviest buffer spring and buffer your gun will tolerate. The H3 is a good one. I forget which spring I have in mine. If you can delay the bolt from opening for a few more milliseconds, it should temper that bark.

    The other question is....what ammo are you using?
     

    rouchna

    Defund the ATF
    MDS Supporter
    Nov 25, 2009
    5,951
    Virginia
    I use the Q9 Heavy buffer from Heavybuffers.com. I've had no issues and it is super quiet.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I use the Q9 Heavy buffer from Heavybuffers.com. I've had no issues and it is super quiet.


    I have the Q9.

    OP, are you going to be at the Duffy's silencer shoot this weekend? You can try my Q9 with a Wolf spring. It is actually out of the rifle at the moment.
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    As Teratos said, use a Q9 Buffer. The H3 is too light for a blowback 9mm, especially a suppressed one.

    A Superior Shooting Solutions .308 Flat Wire Buffer Spring will slow it a bit. It may be too much though, so the standard 5.56 Superior Shooting Solutions Flat Wire Action Spring may be best.

    Be sure to check for Faux Gas Key contact/gap with the lower receiver.
     

    AssMan

    Meh...
    MDS Supporter
    Jan 27, 2011
    16,211
    Somewhere on the James River, VA
    As Teratos said, use a Q9 Buffer. The H3 is too light for a blowback 9mm, especially a suppressed one.

    A Superior Shooting Solutions .308 Flat Wire Buffer Spring will slow it a bit. It may be too much though, so the standard 5.56 Superior Shooting Solutions Flat Wire Action Spring may be best.

    Be sure to check for Faux Gas Key contact/gap with the lower receiver.


    Excellent. I'll check out the Q9 and flat spring.


    Sent from my iPhone using Tapatalk
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,643
    MoCo
    Heavy buffers sells a even heavier buffer for suppressed 9mm carbines.

    FWIW Springs will not affect the chamber opening rate in a blowback firearm. This is well explained Chinn if you want to read up on the math. 9mm has something like 20kN to deal with IIRC. A couple N difference in a spring is a tiny fraction of a single %. Its FAR more effective to solve the problem w/ bolt(+buffer) mass in a blowback system.
     

    TheDevilHimself

    , Duffy's Gun Room
    Industry Partner
    Jul 15, 2011
    1,807
    Sparks, MD
    Thanks! Only took a year.
    If you ever get down Virginny way, let me know. I'm West of Charlottesville, not far from the BR Parkway and the Wintergreen ski resort.


    Sent from my iPhone using Tapatalk

    10-4, buddy. I'll be sure to let you know the next time I'm down that way.
     

    AssMan

    Meh...
    MDS Supporter
    Jan 27, 2011
    16,211
    Somewhere on the James River, VA
    Heavy buffers sells a even heavier buffer for suppressed 9mm carbines.

    I saw that they have a Q9 (8.5oz) and Q9-T (12oz). I'm not certain which to purchase. Both are heavier than the H3 @ 5.4oz. With a 5" barrel, the gun will only be run suppressed.

    Neither one is cheap, but damn, the Q9-T is $$$ at $140. Not sure if it's worth it and/or wonder what issues may arise.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I have the 8.5 ounce. Had it out today. Here is a video I did comparing different loads.

     

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