Anyone actually have data on a 10" with AGB?
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    Default Anyone actually have data on a 10" with AGB?

    It looks like the AGR that I got with my Brownell's kit is for a 10" barrel and not a 14.5", as was the common thought process. So through all my searching here I've found numerous discussions about 10" uppers and their gas port size, vented port size, and all kinds of other good info to learn. But in the few threads I've been able to find about AGRs on 10" uppers, no one comes back and actually reports on whether installing them was worth it.

    At this point, I'm ready to modify my AH upper to accept a new vented gas block, but whether that's a vented AGR or just a straight up vented block is the question. I've read numerous accounts of how the vent made things better from guys like RegluarGuy and Augee (with the corresponding barrel gas port mod, of course), but does anyone have any feed back on using an AGR? Those that ask the question here seem to never come back and report their results. It seems like it would be at least a little better (1.4mm vs 1.5/1.6mm gas port and a vent), but maybe just doing the vent is the easier way to go, operability-wise and I just sell the AGB. Thoughts?

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    With a 1.6mm gas port, the 1.4mm suppressed setting, and 1mm vent, my Surefire Socom SB was still slightly overgassed. For reference, the SB has even less back pressure than a Socom Mini.

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    There has been debate about this, most of the input coming from our EU brothers/sisters. IIRC, @baljar was always of the opinion that with the self regulating plain vented 10” gas block there is no need for the added mechanics of an AGB. @Montrala I think is of the same opinion unless you are trying to tune the pressure for precision shooting.

    For me, I agree with baljar, why complicate things with springs and things when it’s not necessary. BUT, I’ve also never shot a 556 with an AGB.and if I was a pre idiom shooter is probably look to buy a Burk AGB that he seems to coming out with for 556 (or may have already released it). I have a 308 versioning it. I’m not a big fan of the Norwegian AGB design, especially Version I (IINM the plunger/spring is open to the elements?).

    For Burk AGB see link:

    https://www.vikingtactics.de/Heckler...ml?language=en
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    I use AGB on my 11" "A5" (MR223A3) to use lighter buffer and softer recoil spring for 3Gun shooting. For normal use i stock configuration, w/o suppressor, I do not see need. However I believe it gives some benefits when suppressor is attached (lower cycling speed makes things a bit easier on the gun reducing wear and promoting better reliability).
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    Quote Originally Posted by Montrala View Post
    I use AGB on my 11" "A5" (MR223A3) to use lighter buffer and softer recoil spring for 3Gun shooting. For normal use i stock configuration, w/o suppressor, I do not see need. However I believe it gives some benefits when suppressor is attached (lower cycling speed makes things a bit easier on the gun reducing wear and promoting better reliability).
    Thanks for responding.

    Whose AGB are you using, HK or Burk? If HK, is it Norwegian Version or A5 with front facing regulator?

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    HK Norwegian version 2nd Gen (from ZiB).

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    Thanks for the replies. If I were to put a new gas block on my 10" (which I'm pretty certain of), then 1.5mm for the gas port seems to be the sweet spot. I'm tired of having to run a XH buffer and Slash spring to make it function suppressed.

    From the science side of things, wouldn't a 1.4mm (AGB) setting have to be at least a little less gassy then just a straight vented gas block w/ a 1.5mm/1.6mm gas port? Perhaps it's not measurable at the shoulder. I also totally understand the argument against more moving parts w/ the AGB, though.

    Quote Originally Posted by tlrgsxr
    With a 1.6mm gas port, the 1.4mm suppressed setting, and 1mm vent, my Surefire Socom SB was still slightly overgassed.
    Out of curiosity, @tlrgsxr , have you measured your AGB vent? Mine is less than 1mm so I was wondering if that might be the case with yours. I don't know how much less, as the smallest pin gauge I have is a .99+ mm, but I'm guessing it's .035" to match the non-AGB vent size.
    Last edited by gatordev; 11-06-2019 at 08:42 PM.

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    I measured all the sizes I mentioned previously. I’d reconfirm, but I sold it.

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    I picked up a 10.4” barrel and an HK AGB from Hurricane Butterfly. The barrel has a 1.7mm port. The AGB listing said it’s for 14.5″ & 16” & 20″ barrels. The measurements for the AGB are N=1.7mm, S=1.2mm, Vent .9mm.

    I don’t currently have a suppressor, so I could only test un-suppressed with the AGB set to “N”. When shooting with the HK416 buffer spring (red stripe) and buffer (red dot), the gun was under-gassed. It would eject the fired case, but would not cycle a new round. I swapped the HK416 spring for a standard carbine spring and used the HK416 buffer, the gun cycled the empty case @ 4 o’clock, cycled in the new round, and locked open on last round. I’ve shot a couple hundred rounds of 55g and 62g with no issues.

    My next test will be to see what happens with a suppressor and the AGB set to “S”, but that won’t be until the March/April time frame...
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    I've an AGB that i'm working on for a member here and I just got some measurements from it.

    The vent is just about .9mm and the port sizes on the switch are 1.1mm and 1.8mm.

    The 1.8mm is a wash since the gas will be fully controlled by the barrel gas port so the 1.8mm allows full through flow and the 1.6mm barrel port would be restricted to the 1.1mm of the suppressed settings.

    Others have listed the suppressed port at 1mm.

    I am starting to get the feeling that much of the stuff Zib offered and now Brownells was QC rejects for tolerance issues.
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