The heaviest 9mm AR rifle buffer

Discussion in 'Rifle Country' started by zaitcev, Aug 7, 2019.

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  1. zaitcev

    zaitcev Member

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    I have a 9mm rifle that's mostly used as a test platform for Fraurem adapters for PPQ magazines. Shooting it, I noticed that there's a lot of fowling on internal parts, much more so than in a regular pistol. I take it to mean that the extraction pressure is still higher than ambient enough to cause this kind of venting.

    Although the pressure is not high enough to make shooting unsafe, and the brass looks fine, this is still annoying. I'm thinking about stepping up the buffer weight. Currently I have a KAK Ind. 9mm Carbine buffer of 5.4 oz. Anyone have any suggestions about this? I would prefer not to go too out of the ordinary, like the TacCom magnetic buffer.
     
  2. shoobe01

    shoobe01 Member

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    Blowbacks get dirty. If the case shows no signs of pressure, and you aren't getting parts breakage, etc. I'd be inclined to leave it alone.

    But if a test gun... would be good to know actual bolt speed, match to the most common speed. Anyone know the baseline or a good way to measure that without excessively crazy expensive equipment?
     
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  3. someguy2800

    someguy2800 Member

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    what recoil spring are you using? I have a extra power AR10 buffer spring which helped a lot to tame the bolt speed.
     
  4. Walkalong

    Walkalong Moderator Staff Member

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    Yep. pressure and powder speed are the biggest factors in clean brass in a blow back AR in 9MM. My N320 plinker loads come out far cleaner than my full power loads with medium speed powders of any kind.

    But I gave up and accepted that 9MM cases from the AR would be dirtier years ago, and I am at peace with it.
     
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  5. rbernie
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    rbernie Contributing Member

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    Speaking from lots of experience – increasing buffer weight in a blowback pistol-chambered AR will give you increased bolt bounce and eventually provide the excitement of an out-of-battery. Moving to a stiffer buffer spring weight is a far better solution to manage the carrier.

    None of my blowback ARs (45, 40S&W, and 9x19) use anything other than standard weight buffers.
     
  6. shoobe01

    shoobe01 Member

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    I also forgot to actually contribute: it varies. I have an SBR lower that uses a normal chrome silicon spring (though, changed regularly) and an H buffer for... everything. 12.5" 5.56, 10.5" .300BLK, 10.5" 9mm. Suppressed and not. Works like a charm in all of them. Many others have entirely different performance in their guns, have seen a few other threads like this where someone knowledgable says: try it, see what happens. Hard to say.

    :)
     
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