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Thread: Vertical Stringing when Suppressed

  1. #11
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    I agree with not ruling out barrel nut. After I thought the optic might be the problem I also thought the barrel could possibly be loose. I didn't take off rails or check the barrel nut specifically, but it feels rock solid when I try to flex it by hand. After shooting good groups unsuppressed I thought this a little less likely.

    In the first picture, you can see the 3 rounds at the bottom that were shot unsuppressed that did not string.

  2. #12
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    Vertical Stringing when Suppressed

    Vertical stringing while prone can be due to breathing.


    Sent from my iPhone using Tapatalk

  3. #13
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    What concerns me after reading your post and the responses twice is the amount of displacement at so short a range with the suppressor on Rifle A.

    Can and or have you inspected the crown of the offending rifle?

    I would pull of the flash-hider and if necessary mount it again without the shims, heck might be way better without the shims. I cannot say that I am familiar with the particular device, but when firing suppressed would it in any way mater?

    At such a short range I'd be tempted to throw some BUIS on and not worry about an optic acting up occasionally. Also pound some rounds down range unsuppressed first.
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  4. #14
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    Could just be the gun. I had a 10.5" noveske with an 8+ moa shift out of a known g2g can. Noveske basically said the gun was a shit show and gave me my money back. Nothing was in spec basically. Not even the lower,lol

    Id swap out muzzle devices amd go from there next.

  5. #15
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    Here is a picture of the crown of “Rifle A”.

    3.jpg

    I sent my OP and the picture of the crown to BCM and they wanted to know if I used a Geissele alignment rod. I told them no, I don’t own a Geissele rod, and they said to ship my upper to them without the flash hider or the suppressor. They included a prepaid shipping label. I sent the upper to them and received it back about two weeks later without any information included. I emailed them asking what they found.

    BCM Response:
    “We confirm we received your upper receiver group back to our facility for inspection. We fully inspected and QC’d all of the individual components of the upper receiver group. These were all found to be well within spec.

    We can only assume that there may be an issue with the muzzle device that was installed on the weapon system. If the muzzle device was not verified to be concentric prior to installation of the suppressor, this would cause an issue. We would recommend installing the muzzle device to the manufacturer’s specifications and using a good alignment rod, such as a Geissele Alignment rod to verify concentricity before installation the suppressor. Once verified and the suppressor has been installed, we suggest verifying concentricity again with the alignment rod.”


    So according to BCM, the upper isn’t the problem.

    I now email Surefire with my OP and they respond requesting pictures of the Warcomp and asking if there has been any baffle strikes. I send them pictures of the Warcomp and tell them no, there hasn’t been any baffle strikes.

    I get a response saying the Suppressor Division would like to inspect my upper (w/o BCG) with the Warcomp installed as when I shot, as well as inspect the SOCOM300-SPS suppressor.

    I ship the Upper, Warcomp, and Suppressor to Surefire.

    About 6 weeks later I get back my upper and suppressor and what appears to be a new 7.62 Warcomp. No information is included in the packaging.
    I email Surefire and ask if the old Warcomp was out of spec, or the cause of my problems.

    Surefire Response:
    “No issues with the original WARCOMP. However, to rule that out as an issue it was replaced. There were some minor spec issues with the Suppressor that were addressed.”


    I ask if the “minor spec issues” would be individual to “Can1”, or is there a possibility of the same issues occurring within that batch of suppressors? (since “Can1” and “Can2” have sequential serial #’s and SF only inspected “Can1”)

    I also ask, if possible, could they highlight what the spec issues with the suppressor were?

    Surefire responds saying the issues would be individual to that can, with no detail about what the actual spec issues entailed.


    I install the new Warcomp and finally get to the range. The results are the same as before. Large vertically strung groups whenever “Rifle A” is suppressed (with either “Can1” or “Can2”).
    Again, this is shooting factory Barnes 110gr Black Tip at 40 meters.

    There IS vertical stringing with:
    “Rifle A” suppressed with “Can1” - (11” Extreme Spread) – (Picture 1)
    “Rifle A” suppressed with “Can2” - (6.25” E.S.) – (Picture 2)

    There IS NOT vertical stringing with:
    “Rifle A” unsuppressed - (1.25" E.S.) – (Picture 3) - (Its either not stringing, or the stringing is too small to tell for sure. I really should've fired a 10 rnd group.)
    “Rifle B” unsuppressed - (~1” E.S.)
    “Rifle B” suppressed with “Can1” - (~1” E.S.)
    “Rifle B” suppressed with “Can2” - (1” E.S.)

    1.jpg2.jpg3.jpg

    Notably, each time testing, “Rifle A” with “Can1” Extreme Spread is double the size of the E.S. with “Can2”. These E.S. numbers with each can have also been fairly consistent from range trip to range trip (~12” with “Can1”, and ~6” with “Can2”).


    Lets list the possibilities that I see:

    -Barrel threads not concentric to the bore. It is slight enough that it is unnoticeable with a regular FH, but with the added length of a suppressor, the effect is compounded and noticed.

    - There isn’t an issue with any single part, but a “tolerance stacking” type of issue.

    Solutions:

    -Buy a new barrel and see if problem is remedied.

    -Buy alignment rod to verify the non-concentricity. Then buy a new barrel...

    -Break apart entire upper and reinstall barrel, gas block, the whole 9 yards. Im not sure exactly what BCM’s QC process entails, but I would assume they would have checked it all out for proper specs and assembly when I sent it back to them, considering it’s a factory upper. Still, this is the only thing I can think of that doesn’t entail a new barrel.

    Any other ideas?

  6. #16
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    Quote Originally Posted by Randall View Post
    Here is a picture of the crown of “Rifle A”.

    3.jpg

    I sent my OP and the picture of the crown to BCM and they wanted to know if I used a Geissele alignment rod. I told them no, I don’t own a Geissele rod, and they said to ship my upper to them without the flash hider or the suppressor. They included a prepaid shipping label. I sent the upper to them and received it back about two weeks later without any information included. I emailed them asking what they found.

    BCM Response:
    “We confirm we received your upper receiver group back to our facility for inspection. We fully inspected and QC’d all of the individual components of the upper receiver group. These were all found to be well within spec.

    We can only assume that there may be an issue with the muzzle device that was installed on the weapon system. If the muzzle device was not verified to be concentric prior to installation of the suppressor, this would cause an issue. We would recommend installing the muzzle device to the manufacturer’s specifications and using a good alignment rod, such as a Geissele Alignment rod to verify concentricity before installation the suppressor. Once verified and the suppressor has been installed, we suggest verifying concentricity again with the alignment rod.”


    So according to BCM, the upper isn’t the problem.

    I now email Surefire with my OP and they respond requesting pictures of the Warcomp and asking if there has been any baffle strikes. I send them pictures of the Warcomp and tell them no, there hasn’t been any baffle strikes.

    I get a response saying the Suppressor Division would like to inspect my upper (w/o BCG) with the Warcomp installed as when I shot, as well as inspect the SOCOM300-SPS suppressor.

    I ship the Upper, Warcomp, and Suppressor to Surefire.

    About 6 weeks later I get back my upper and suppressor and what appears to be a new 7.62 Warcomp. No information is included in the packaging.
    I email Surefire and ask if the old Warcomp was out of spec, or the cause of my problems.

    Surefire Response:
    “No issues with the original WARCOMP. However, to rule that out as an issue it was replaced. There were some minor spec issues with the Suppressor that were addressed.”


    I ask if the “minor spec issues” would be individual to “Can1”, or is there a possibility of the same issues occurring within that batch of suppressors? (since “Can1” and “Can2” have sequential serial #’s and SF only inspected “Can1”)

    I also ask, if possible, could they highlight what the spec issues with the suppressor were?

    Surefire responds saying the issues would be individual to that can, with no detail about what the actual spec issues entailed.


    I install the new Warcomp and finally get to the range. The results are the same as before. Large vertically strung groups whenever “Rifle A” is suppressed (with either “Can1” or “Can2”).
    Again, this is shooting factory Barnes 110gr Black Tip at 40 meters.

    There IS vertical stringing with:
    “Rifle A” suppressed with “Can1” - (11” Extreme Spread) – (Picture 1)
    “Rifle A” suppressed with “Can2” - (6.25” E.S.) – (Picture 2)

    There IS NOT vertical stringing with:
    “Rifle A” unsuppressed - (1.25" E.S.) – (Picture 3) - (Its either not stringing, or the stringing is too small to tell for sure. I really should've fired a 10 rnd group.)
    “Rifle B” unsuppressed - (~1” E.S.)
    “Rifle B” suppressed with “Can1” - (~1” E.S.)
    “Rifle B” suppressed with “Can2” - (1” E.S.)

    1.jpg2.jpg3.jpg

    Notably, each time testing, “Rifle A” with “Can1” Extreme Spread is double the size of the E.S. with “Can2”. These E.S. numbers with each can have also been fairly consistent from range trip to range trip (~12” with “Can1”, and ~6” with “Can2”).


    Lets list the possibilities that I see:

    -Barrel threads not concentric to the bore. It is slight enough that it is unnoticeable with a regular FH, but with the added length of a suppressor, the effect is compounded and noticed.

    - There isn’t an issue with any single part, but a “tolerance stacking” type of issue.

    Solutions:

    -Buy a new barrel and see if problem is remedied.

    -Buy alignment rod to verify the non-concentricity. Then buy a new barrel...

    -Break apart entire upper and reinstall barrel, gas block, the whole 9 yards. Im not sure exactly what BCM’s QC process entails, but I would assume they would have checked it all out for proper specs and assembly when I sent it back to them, considering it’s a factory upper. Still, this is the only thing I can think of that doesn’t entail a new barrel.

    Any other ideas?
    Have you shot the upper with no muzzle device? If so what we're the results?

  7. #17
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    Quote Originally Posted by themonk View Post
    Have you shot the upper with no muzzle device? If so what we're the results?
    No, I hadnt thought of shooting without a muzzle device.

    I can probably get to the range this weekend and fire a couple groups with the MD, and then without. What is your thought process behind this? Simply to see if anything changes?

  8. #18
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    Quote Originally Posted by Randall View Post
    No, I hadnt thought of shooting without a muzzle device.

    I can probably get to the range this weekend and fire a couple groups with the MD, and then without. What is your thought process behind this? Simply to see if anything changes?
    I deal with this multiple company BS a lot. You need to do your own troubleshooting to find the culprit. In my opinion first step is to double-check BCM - do you have the problem without a muzzle device. If no it's the not the upper / crown.

    Next I would put on the muzzle device without a can and see if you have the problem. If you do then the problem is either with the muzzle device itself or with the concentricity of the barrel. If no issue you know it has to do with the can or can / muzzle device interface.

  9. #19
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    My bet is on the threads.
    I’ve seen this only four times and three of the four times it was hard to diagnose due to each manufacturer having different tolerances and then you start getting tolerance stacking and they blame each other, etc. It’s a nightmare. The fourth one was a bad muzzle device that caused the issue.
    Sounds like suppressor is ruled out.
    Since you had the muzzle device swapped, Your best solution might be to have the barrel cut and re threaded but it’s hard to say without it being in hand.
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    In 2014, a RDS and a WML are pretty much mandatory for a defensive long-gun.

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  10. #20
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    Im thinking it is the threads as well. Between the new MD, and the suppressors working fine on “Rifle B”, I don’t see how it can’t be related to the barrel in some way.

    At this point I’m honestly tired of messing around with it and just want it fixed.

    I haven’t ever needed a gunsmith to get work done before. I know I’ve seen ADCO mentioned, with positive feedback if my memory serves me right.

    From ADCO, I can get the barrel cut and threaded for $75. The problem with this is that I have a 9” barrel with an 8” rail. Cutting could prove to be an issue as there is only 5/16” space between the rail and the suppressor.

    ADCO also offers replacing destroyed threads for $155.

    “We turn down, thread, and install new threads just like we do with the threaded extension service. This way you keep the barrel length.”

    Im not a machinist in the slightest. Is there any downside to having them replace the threads vs cutting and threading? (Other than monetary of course)

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