Blow Back Ar-15

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  • andy41567

    Active Member
    Oct 1, 2018
    176
    So I have been noticing on my one AR that I seem to get a lot of blow back that I seem to notice in my face. I of course have safety glasses on and I am the shooter so I can't quite see what is happening. But in doing some research I have read it could be coming from the CH.

    The specs are... Stag upper and lower and BCG. I checked the rings in the bolt to appear to be fine and not lined up. 18" barrel with mid-length gas system, not adjustable. Gas tube is not damaged. Gas key looks to be fine. But not sure I know what I am looking at. Ammo is the same I have shot on all guns and not noticing this problem on any other guns. Has an h1 buffer. Gun just feels like a cannon when shooting it compared to my others.
     

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    threegun

    Active Member
    Jan 26, 2013
    639
    Westminster
    Could be over gassed (casings at 1 or 2 oclock). Where are the casings landing? Adjustable gas block, heaver buffer, or Tubbs flat spring could help.
     

    andy41567

    Active Member
    Oct 1, 2018
    176
    I don't know what the casings look like. Your talking about how they are ejected, right?
    As for headspacing... I am assuming when the gunsmith installed the new barrel he checked that. But I had it happen on both barrels. It's done this from day 1 as a new gun. I then changed the barrel, bcg, handguard and gas system(non adjustable). Now a mid-length. And it still does it.

    I can purchase a no go gauge can't I to check it myself right.

    Sent from my SM-G965U using Tapatalk
     

    danb

    dont be a dumbass
    Feb 24, 2013
    22,704
    google is your friend, I am not.
    looking at your muzzle device (brake), I kinda suspect that. Looks pretty aggressive, you might be getting some blowback from that. See what happens if you take it off and replace it with a standard flash hider.
     

    andy41567

    Active Member
    Oct 1, 2018
    176
    OK well I can give that a shot to. But I just put that on as well. It's new. Problem was there before that.

    Sent from my SM-G965U using Tapatalk
     

    John from MD

    American Patriot
    MDS Supporter
    May 12, 2005
    22,731
    Socialist State of Maryland
    Try to see where the cases are ejecting. If it is in the 1 to 3 o'clock position, a heavier buffer may help your problem. The quick fix with RTV works pretty well if it's not the buffer.
     

    kdmag88

    Active Member
    Jan 10, 2018
    125
    I just meant do the casings looks stretched or 'burnt up' looking. Like the case wasn't sealing in the chamber properly and high pressure gas was leaking into the receiver. If it did this before and after changing all the things you listed, I agree with the others, it's probably just very overgassed and adjustable gas block should help.
     

    andy41567

    Active Member
    Oct 1, 2018
    176
    If it was already doing that, then its probably not the muzzle device.

    Might try a heavier buffer and spring. If you have a light carbine buffer in there add some weight.
    OK I was thinking that to. It is a carbine buffer. And I have an H3 coming for my other gun that has an h2 in it now. So I will pull the h2 and put it in that blow back gun and see if that helps

    Sent from my SM-G965U using Tapatalk
     

    andy41567

    Active Member
    Oct 1, 2018
    176
    I just meant do the casings looks stretched or 'burnt up' looking. Like the case wasn't sealing in the chamber properly and high pressure gas was leaking into the receiver. If it did this before and after changing all the things you listed, I agree with the others, it's probably just very overgassed and adjustable gas block should help.
    OK perfect now I understand better. Unfortunately I never knew to look at the casings. But I will when I shoot it again in the next couple of days.

    Sent from my SM-G965U using Tapatalk
     

    andy41567

    Active Member
    Oct 1, 2018
    176
    Try to see where the cases are ejecting. If it is in the 1 to 3 o'clock position, a heavier buffer may help your problem. The quick fix with RTV works pretty well if it's not the buffer.
    You know just as I was replying to everyone. I kinda remember that I did notice that this gun seems to eject the casings a lot faster and farther then my other guns. So that would support this theory right.

    Sent from my SM-G965U using Tapatalk
     

    John from MD

    American Patriot
    MDS Supporter
    May 12, 2005
    22,731
    Socialist State of Maryland
    I just noticed that you have an 18in barrel and mid gas. I have one of those and it needed a H3 buffer and a Tubb flat spring to calm it down. Well, you have an H2 and are getting an H3 so I'm sure you will be able to work it out.
     

    holesonpaper

    Active Member
    Mar 10, 2017
    913
    Hazzard county
    My vote - adjustable gas block... I’m a convert and run them on all my AR’s just for this reason... As a lefty who runs supressors, I know all about the sh-t blowing in your face...
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    Ejection pattern is not a reliable indication of gassing.

    Overgassed is a common problem with most AR's.

    It may need to be inspected to determine what's going on.

    Is the Gas Key impacting the lower receiver? That will cause harsh recoil.

    You can adjust at the Gas Block (BRT Gas Block Port Restrictor, BRT Restricted Port Gas Tube, or a SLR adjustable Gas Block), or you can adjust on the back end (Buffer, Buffer Spring).

    Adjustable Gas Keys and Bolt Carriers are not worth using.
     

    Magnumite

    Ultimate Member
    Dec 17, 2007
    6,561
    Harford County, Maryland
    I just noticed that you have an 18in barrel and mid gas. I have one of those and it needed a H3 buffer and a Tubb flat spring to calm it down. Well, you have an H2 and are getting an H3 so I'm sure you will be able to work it out.

    I thought the longer gas system actually reduced gas problems. I used a rifle length upper with full skirt carrier (M16) on a standard carbine lower and it wouldn't cycle. A short skirt carrier did stop the lack of cycling but it cycled softer.

    I guess the midlength is just enough to still cause issues. Learn something new every day.
     

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