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Thread: Buffer and spring recommendations for 300 blackout

  1. #1
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    Buffer and spring recommendations for 300 blackout

    The info I have come across seems conflicted; No H2 or H3 buffer vs H2 buffer is standard.
    Any insight is appreciated.

  2. #2
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    I have an AAC factory-built 9" upper and they recommend an H2 buffer.

    Straight from their website: "ACTION SPRING/BUFFER
    Use either the standard USGI M4 or the HK 416 spring. For buffers, select a 4.6 oz (130 gm) H2 or an HK-416 bufferthough a 5.5 oz (155 gm) H3 buffer may be a good choice if you donít intend to shoot subsonic without a sound
    suppressor or typically shoot supersonic ammo. Do not use a solid 9mm buffer as it may cause bolt bounce."

    But it also depends on what you plan on shooting. Supersonic vs subsonic vs subsonic suppressed may all cycle better with different buffers in your particular gun. Gas port size will also be a factor.
    Last edited by officerX; 05-30-21 at 22:00.

  3. #3
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    Thank you officerX !!
    Mainly shoot sub suppressed with 10.3 barrel.

  4. #4
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    LARB MOD2 buffer SprinCo white spring
    FFL/SOT

    Chuck Norris has to maintain a concealed weapon license in all 50 states in order to legally wear pants.

  5. #5
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    Like most of my other carbines and pistols (5.56), I did a basic carbine spring and H3 on my 9". No issues and a nice shooter.

  6. #6
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    My Ballistic Advantage 8.3" Hanson barrel requires a heavier set up than their recommendation. I believe the port was drilled too big. I was using an H3 with a carbine spring. I believe they recommended an H1 when I reached out to them, but it's been a few years since then. I recently installed a BRT gas tube and switched to an A5 buffer tube and A5H2 buffer. This has helped tremendously.

  7. #7
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    There isn't a single answer IMO. How is your rifle configured? Barrel length, gas system (pistol, mid, rifle length), intended bullet use (super, subs, both), suppressed? All will have an effect on cycling reliability. For instance, I have a 9.5" pistol gas that runs strictly sub/suppressed with a carbine spring/buffer. runs EVERYTHING that's subsonic 100%. Change it's mission and it might not be 100%. Balance it out to run sub/super and at the fringes may be iffy. JMHO YMMV

  8. #8
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    I bought a Ruger 10.5in. 300blk pistol (should have just built one) and it shot both subs and supers fine with the H buffer and stock spring. Then I suppressed it and my problems began. Couldn’t get it to cycle. Got a BRT tube no difference. They had me send it back and they reworked it. But in the mean time I talked to Ruger who recommended a lighter buffer. I bought KAK buffer kits (the heavy and the light) and tried everything before finally settling on the 2.6. It now runs great suppressed. I only point this out to show that sometimes you just have to play with them to get them to work correctly.

  9. #9
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    I have a PSA 8.5” barrel that has run everything 100%, subs and supers, suppressed or non. Down side is I’m sure the gas port is massive and it’s not all that quiet suppressed. I’m going to tear it down, measure the port size, and add a switchable gas block if I can find one I like.

    I have a friend with a bunch of Hornady 190 gr Sub-X that won’t run in his AR, Sig Rattler, or buddy’s DD M4. I’m pretty sure mine will eat it just fine.

    I had been running an H2 with a standard Carbine spring, it’s now running an A5H2 setup in an attempt to quiet it down with the can a bit. Can share gas port specs when I get it apart.

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