AR Upper build-300 AAC Blackout...

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  • billybob44

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    Sep 22, 2010
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    Need some help/advice from you AR Pros out there on INGO...

    I have a new AAC brand 16" barrel, in the 300 AAC Blackout caliber, with the factory low profile (Non-adjustable) gas block that came with it.
    The gas port location on the barrel supports a pistol length gas tube.

    This:https://www.midwayusa.com/product/1...roduct-shipped-today-product-description-link will be the muzzle break.
    I will be using a new PSA Nickle Boron bolt carrier group (if that makes any difference??).

    My primary loads will be 110gr. Nosler and V-Max rounds, loaded up to the higher end of specs from these Co. data lists. I will probably move up to a 125gr. Ballistic tip later.
    At this time I do not ponder on any suppressed loading.

    I would like to use this upper build on one of my A2 (Full length) stock lowers.


    My question is: Do I use the Rifle buffer and spring for this upper, or should I start with a Carbine length buffer and spring??

    I have both to try, and I just ask for thoughts for the best cycle of the bolt carrier group??

    I kind of just now got the .223/5.56 rounds/uppers where I want them, and am going to see what the Blackout does for me??

    Thanks in advance..Bill.
     
    Last edited:

    Ggreen

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    Try the buffer you have. Supersonic rounds through a pistol gas system have never given me trouble with any buffer set up.
     

    BiscuitsandGravy

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    Try the buffer you have. Supersonic rounds through a pistol gas system have never given me trouble with any buffer set up.

    I agree with Ggreen. You should be fine since you say your going to run them on the upper end. You'll be surprised how much punch a 300 can have. We even run JP high power buffer springs with no issues.

    What flavor of powder are you planning to use? One thing I've found is to de-burr and chamfer your case mouths. It will help with insertion of the base of the pointy part into the case.

    YMMV of course... :ingo:

    Re; NiB BCGs... Just ran my dissembled NiB BCG from the 16" 300 in the ultrasonic cleaner for 480 seconds. Came out nice and clean. Applied some Tri-flow oil to bolt and cam pin- smooth as silk.
     
    Last edited:

    billybob44

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    H-110...

    What flavor of powder are you planning to use? One thing I've found is to de-burr and chamfer your case mouths. It will help with insertion of the base of the pointy part into the case.

    Yeah, between cutting down .223/5.56 cases to re-form to 300, I KNOW that I have de-burred+chamfered more than a few times..HA. HA..
    I have been using H-110 under Flat Base bullets from Nosler and Hornady. Yes..without the proper chamfer I have damaged a few cases..

    Thanks for the replies..Bill.
     

    bwframe

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    :popcorn:

    This guy has a huge amount of 300 ACC Blackout videos on most aspects of the platform:


    [video=youtube;axgd6zQm2JU]https://www.youtube.com/watch?v=axgd6zQm2JU&t=406s[/video]
     
    Last edited:

    1stLast&Always

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    I researched BO for months before I built mine. What I read in a few places said run carbine buffer on pistol gas. This is my setup and I have zero problems.

    I also use IMR 4227, which has stellar reviews for super or sub. I dont think you'd need adjustable gas just getting in for the occasional spin?

    Love the TNT 125 gr. Have loaded some 150 Interlocks though I haven't gotten to shoot them yet.
     
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