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Thread: Adjustable AR buffer not sufficient: Help

  1. #1

    Adjustable AR buffer not sufficient: Help

    I'm running a DD 11.5" bbl, BCM BCG, Vltor A5 buffer system. UNSUPPRESSED, it runs fine with Sprinco Green spring & either A5H3/A5H4.
    Note: AMMO-all shooting done with M193. It functions flawlessly either suppressed or not, and is a fine, soft shooter.
    SUPPRESSED with an AAC-556-SD can, it acts over-gassed: ejects to 1:00.

    Got a HeavyBuffer A5 buffer tungsten weight kit, built a 10.2 oz. buffer, coupled with a Wolff spring...ejects to 2:30-3:00. I just can't get it to 4:00-4:30.

    I do not want to install or rely on an AdjGB.

    What the heck am I doing wrong?

  2. #2
    I'm confused. If it shoots just fine, then why do you care about ejection pattern? Especially when 0300 is generally considered part of the sweet spot, so 0230 to 0300 is something I would never worry about, doubly so when you're saying it's got a good recoil impulse. Issues like ejector spring tension, extractor tension, etc. call also play in role in ejection pattern.

    You could always tune the gas system by using one of those adjustable bolt carriers, switching to an LMT e-carrier, or grabbing one of the BRT EZTune gas tubes.

  3. #3
    I was under the impression that I should tune it to eject to b/w 4:00-4:30. You did make me feel better about a 3:00 pattern.

    I prefer using non-finicky things, and I need the SBR to run suppressed & Unsuppressed. So I worry about the EZT tune, AdjGB's and AdjBCG's.
    For now, I run it with the Sprinco GRN & A5H4 when UN-canned. Today was my first suppressed shooting with the 10.2 oz. and the Wolff. I guess I was just surprised that it didn't "perfectly" pattern the casings at 4-430. I'm not real concerned with the over-gassing causing a slight decrease in velocity. I was looking to decrease the fouling in the receiver, and prevent long-term damage to the bolt/chamber lugs.

    Thanks for your response, I truly appreciate someone getting back to me.

  4. #4
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    Quote Originally Posted by Tank Boss View Post
    I was under the impression that I should tune it to eject to b/w 4:00-4:30. You did make me feel better about a 3:00 pattern.

    I prefer using non-finicky things, and I need the SBR to run suppressed & Unsuppressed. So I worry about the EZT tune, AdjGB's and AdjBCG's.
    For now, I run it with the Sprinco GRN & A5H4 when UN-canned. Today was my first suppressed shooting with the 10.2 oz. and the Wolff. I guess I was just surprised that it didn't "perfectly" pattern the casings at 4-430. I'm not real concerned with the over-gassing causing a slight decrease in velocity. I was looking to decrease the fouling in the receiver, and prevent long-term damage to the bolt/chamber lugs.

    Thanks for your response, I truly appreciate someone getting back to me.

    Suppressors in general increase back pressure. A gun that runs fine unsuppressed seeming “over gassed”with a suppressor is normal. Hence the change in ejection pattern suppressed is normal. That’s not being finicky it physics.

    Some suppressors have less back pressure than others. IME the Surefire and KAC suppressors have less back pressure as do the OSS suppressors.

    Changing to a suppressor with less back pressure is the best option to achieve your goal.
    Last edited by HCM; 09-11-2021 at 07:40 PM.

  5. #5
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    Adjustable AR buffer not sufficient: Help

    Agreed with all of the above, I really never pay attention to ejection unless it’s dribbling out. That said, running a green spring with an A5H4 unsuppressed is a bit surprising for a barrel that is supposedly well gassed, especially if it’s a weaker variant of 193 or more appropriately, weak 55gr.

    When was the barrel made? Their MK18 barrels used to be significantly over gassed, not sure if 11.5s were as well.


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  6. #6
    Not sure when the barrel was made, I bought it new from DD in early 2020, when I did the build. I only shoot M193 & M855 (no civilian loads). I meant "finicky" referring to AdjGB's and EZ tune tubes...what can go wrong, will. It runs really smooth/soft unsuppressed with the Sprinco Green and either the H3 or H4.

    What I think may be the issue: my buddy has a top-o-line Surefire suppresser (2" longer x2.5$ more than my AAC) on his 11.5" and his ejects to 4:30. BUT my ACC is very noticeably quieter than his SF. So, I think my AAC must be a can with a lot of back-pressure. I wouldn't trade my AAC for a SF; his has broken twice and been warranty replaced twice. Simply falls apart...and isn't that quiet. Not hating on SF, just my observations.

    I don't mind having 2 buffer/spring combos; 1 combo for can, 1 for no-can. But my issue is, I ALWAYS run it suppressed: doing 180-200+ rds per week; in its "primary state," its suppressed. I was just hoping an adjustable buffer with appropriate weighting (7.9, 8.4, 8.7, 9.2,10.2), coupled with the Sprinco or Wolff, would be the easy button answer.

    Thanks to you all for your time and insight, truly appreciated.

    [I never had ejection issues with my 120mm sabots...]

  7. #7
    A 10 oz buffer is too much. Your AR should be running an A5H2 (5.3 ozs). A rifle buffer weighs 5.2 ozs. It sounds like your barrel is over gassed and you're trying to compensate with an over weight buffer. You can't fix over gassing with a heavier buffer. The gas drive needs to be brought under control.

    As you found out, trying to use ejection angle to tune your AR is a waste of time. However, ejection angle does give you insight to the health of your extractor spring. Ejection at 1 o'clock is a sign your extractor spring is failing and needs to be replaced. Eminent spring failure is further evidenced by the fact that changing to a heavier buffer to slow down carrier speed changes the angle from 1 o'clock to 3 o'clock. The extractor isn't holding the rim securely at the faster carrier speeds. I suggest replacing your old extractor spring with a Colt extractor spring.

    The BRT EZ Tune gas tube has no more moving parts or early failure points than a standard gas tube. It simply has a smaller gas port. Contact Black River Tactical for help selecting the right gas tube. They have excellent customer service. Getting the gas right will give you the added benefit of less schmootz in the receivers and less gas to face.

    https://blackrivertactical.com/WP/Ad...Drive-c6464009
    Last edited by MistWolf; 09-11-2021 at 10:30 PM.
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  8. #8
    Quote Originally Posted by Tank Boss View Post
    Not sure when the barrel was made, I bought it new from DD in early 2020, when I did the build. I only shoot M193 & M855 (no civilian loads). I meant "finicky" referring to AdjGB's and EZ tune tubes...what can go wrong, will. It runs really smooth/soft unsuppressed with the Sprinco Green and either the H3 or H4.

    What I think may be the issue: my buddy has a top-o-line Surefire suppresser (2" longer x2.5$ more than my AAC) on his 11.5" and his ejects to 4:30. BUT my ACC is very noticeably quieter than his SF. So, I think my AAC must be a can with a lot of back-pressure. I wouldn't trade my AAC for a SF; his has broken twice and been warranty replaced twice. Simply falls apart...and isn't that quiet. Not hating on SF, just my observations.

    I don't mind having 2 buffer/spring combos; 1 combo for can, 1 for no-can. But my issue is, I ALWAYS run it suppressed: doing 180-200+ rds per week; in its "primary state," its suppressed. I was just hoping an adjustable buffer with appropriate weighting (7.9, 8.4, 8.7, 9.2,10.2), coupled with the Sprinco or Wolff, would be the easy button answer.
    Yes, AAC cans are notorious for having extremely high backpressure.

    Curious to hear about what broke on the SureFire. Not much that can go wrong. The vast majority of folks I know would pick the SureFire over the AAC in a heartbeat, though most of the advantages of the SureFire are can be negated with a tuned dedicated host (better mounting system, less backpressure, POA/POI shift, etc.); the actual loudness of suppressors on rifles is usually pretty low on the list of traits that professionals look for in a suppressor. Also curious as to what SureFire can it is, the SOCOM556-RC2 is shorter than the AAC 556-SC; if your buddy put a SOCOM762-RC2 on the gun, then yeah, makes sense that it's noticeably louder, given that it's not a 5.56 can, even with the extra length.

    My question is, what could go wrong with the BRT EZTune gas tubes? It's literally just a normal gas tube, except the gas hole is drilled smaller to allow for less gas to come through. Any way that it would fail would kill any normal gas tube, too, so it would be irrelevant; the only other difference would be that the port gets eroded over time, which means you just end up with a normal gas tube over thousands and thousands of rounds. If this is going to be a dedicated suppressed gun, I would absolutely go for the EZTune over tinkering with the buffer; an excessively heavy buffer imparts a very large amount of reciprocating mass with in the gun, and the excess gas still has to go somewhere. Gas regulation here is absolutely the move to go to, rather than adding mass; gas regulation solves the problem, while mass only attempts to cover up the symptoms.
    Last edited by Default.mp3; 09-11-2021 at 11:42 PM.

  9. #9
    Thank you all!
    I'll order the BRT EZ tune tube, Colt extractor springs and an A5H2. I will be able to test three A5 buffer weights (2, 3 & 4), both suppressed and unsuppressed. I have three rifle length springs: Vltor's, Sprinco's Green and Wolff. I'll use the Sprinco if I can get good results with it and the buffers (supra). If anyone has a better idea on which spring, please let me know.

    I'm familiar with the multiple considerations for using a can in a tactical application. Noise reduction, cost & size are the important determinants for me. If SHTF, the other benefits of suppression might come into play. My observations of two separate SF cans on two friends' SBRs are that they are large, expensive, not very quiet, and one of them fails craptastically. I'm not hating on SF cans; I've never owned one. They make good lights.

    Again, thank you all for helping me noodle-out this issue! I will post the results incase anyone is interested.

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