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Thread: BRT custom tune gas port vs heavier buffer

  1. #1
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    BRT custom tune gas port vs heavier buffer

    I have been reading some posts lately about Noveske barrels being over gassed.

    I have a Noveske 16" mid that honestly feels less gassy than a BCM 14.5 mid. I run A5H3 buffers in both. My least gassy rifle is Colt 14.5 carbine with an A5H2. I chose those buffers based in the rifle's ability to get bolt lock with .223 ammo. I never actually tried an A5H4 in either of those rifles yet.

    Anyway, I have another Noveske 14.5 barrel on the way. They're the only game in town for mid-weight CHF barrels, and my 16" rifle is clearly the most accurate that I own. Fully taking into account that I have yet to shoot the new barrel I was debating the merits of using a BRT custom tune gas port to restrict the gas flow or just using heavier buffers.

    Any experience or advice is welcome.

    If anyone is curious the build will consist of a BCM lower with VLTOR A5 receiver extension, VLTOR MUR uppper, Noveske 14.5 barrel with pinned PA EFAB brake, and Geissele MK14 handguard.
    Last edited by Bolverk93; 02-24-18 at 10:33.

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    My experience points to properly setting the gas flow and using the A5H2. Heavier buffers start to push the AR around more than needed as the action cycles.
    The number of folks on my Full Of Shit list grows everyday

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    Quote Originally Posted by MistWolf View Post
    My experience points to properly setting the gas flow and using the A5H2. Heavier buffers start to push the AR around more than needed as the action cycles.
    So I have an older Colt 6920 with the A5 system in it. It runs 100% with the A5H3 and Sprinco green spring. I could probably go up to the A5H4 buffer without issues. Are you saying I should swap the A5H2 back in and tune the exhaust port?

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    Tuning with mass is easy to do, but excessive moving mass makes the sights jump around more.

    Also, the range of adjustment is somewhat limited.

    For example, the difference in spring energy from the lightest to heaviest buffer is only around 10% or so.

    That is roughly the same as changing the port by two sizes.

    The range of adjustment using ports is far wider than buffers and has none of the drawbacks of heavy buffers.

    When suppressors are involved, heavy buffers can help slow down the cycling, but won't meaningfully reduce gas blowback and gas to face issues.

    Only restricting the gas will accomplish that.
    Last edited by Clint; 02-24-18 at 13:18.
    Black River Tactical
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    I believe mass also keeps the bolt carrier group from bounce back.

    So my basic question is, as it comes from Colt is my 6920 slightly overgassed?

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    Quote Originally Posted by EzGoingKev View Post
    So I have an older Colt 6920 with the A5 system in it. It runs 100% with the A5H3 and Sprinco green spring. I could probably go up to the A5H4 buffer without issues. Are you saying I should swap the A5H2 back in and tune the exhaust port?
    Ideally yes, if you wish to further fine tune your AR. Heavier buffers will start pushing your AR around and increase the time and movement it takes to get back on target. However, unless the recoil is excessively sharp (the sign that the buffer is bottoming out too hard) or you're not satisfied with how you're getting back on target, I don't think it's worth worrying about.

    I've been playing with a suppressed 11.5" upper that uses an SLR adjustable gas block. I first tested it with a carbine RE, carbine, H and H2 buffers and Colt carbine action spring. Then it was tested it with an A5 RE, A5H2 buffer and Sprinco green spring. The SLR is click adjustable and each click is one third of a turn. I set the gas block so it would lock back on the last shot with the carbine buffer. Closing the gas block one click resulted in the AR ejecting, but not locking back. In each test, the setting on the gas block didn't have to be changed. Closing the gas block one click resulted in the AR ejecting but not locking back regardless of buffer.

    What I did notice is that recoil was sharpest with the lightest buffer (carbine). It was smoothest with the heaviest buffer (A5H2). The Aimpoint dot moved off the target the least when shooting with the A5H2.. I didn't test heavier buffers because I didn't have any. However, the greater the ratio of reciprocating mass to static mass, the more the reciprocating mass (BCG & buffer) will push the static mass (rifle) around. It's that opposite but equal thing Newton foisted upon us. Don't just take my word for it, however. Switching from an A5H2 buffer to an A5H3 buffer won't result in your AR suddenly being pushed around like a first grader on the sixth grade playground. Test it for yourself.

    So, what does this mean to you and your Colt? The way I see it, you have three paths before you.
    1)If It Ain't Broke, Don't Fix It
    If your AR is working fine, don't worry about it. If the buffer isn't bottoming out too hard and your satisfied with how quick you get back on target, press on.

    2)I'm Not Happy With My Performance Shooting My AR This is a two part path-
    A) The Easy Button- The easiest is to simply try the heavier buffer. The best result is that the heavier buffer works for you. Either you don't notice any extra push, or it's small enough that it's not worth worrying about. It's a win for you with the added bonus you can say "That Mistwolf is a nice guy, but he's full of it." If it doesn't, it's still a win for you because you shot the rifle and found out for yourself instead of just reading about it on the internet. However, I get to be smug.

    B)The Hard Way-The harder path (the one you take after experimenting with heavier buffers) is to try an SLR adjustable gas block, or the BRT custom tune gas port. Both are good choices. The SLR is easier to adjust, the BRT is simpler in design and costs less. Adjusting your gas flow will let you determine for yourself if the A5H2 will give you optimal results or not. Either way, you'll be able to adjust the gas for best performance with each buffer (and spring, if so inclined). Then, you can come back and tell me I'm full of it, or to wipe that smug grin off my face. Choosing this path will allow you to better tune your AR.

    3)Curiosity Killed The Cat
    Your AR works fine, but you have a burning desire to find out if you can make it a little better. Again, it's a two part path. To save time typing, I will refer you to Options A) & B) from 2)I'm Not Happy With My Performance With My AR. Apply "Full of it" or "Wipe Off That Smug Smile" as needed.
    Last edited by MistWolf; 02-24-18 at 20:33.
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    Mistwolf / Clint,

    Thanks for your replies. I try to avoid the gun forum trap of over thinking stuff that doesn't matter, but you guys helped confirm what I was thinking. I should have mentioned in my original post that I have no intention of ever shooting this gun suppressed, but I'll be getting a BRT insert.

    On a side note. I was planning on getting a Colt BCG if I can find one in stock or a BCM. However, Centurion Arms has pretty good prices on their BCG's especially with mil discount. I'm not afraid to spend money on quality, but if the Centurion is mil-spec and the same quality as BCM it's a no brainer. Anyone have insight on that?

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    Centurion BCG are good stuff, but if you want a really good deal on a Colt, Shark arms has them for $125 which is the cheapest I have found. There website is pretty basic and you have to call in your order, but I have ordered from them before and they are GTG. Really good source for other Colt parts as well

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    Everready,

    Thanks for the tip! I'm going to be placing an order with them.

    I'm curious how they are selling them so cheap, though. Other vendors sell Colt BCGs for $180-$200.

  10. #10
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    Yes I was surprised at the pricing. Heard about them on the other forum and have ordered several times with no issues

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