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Getting the AR10 dialed in and bubblegumty .308 ammo

Discussion in 'General Firearm Discussion' started by old11bravo, Jun 29, 2015.

  1. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    Well I had her back out on the range again today in an attempt to prove my theory that bubblegum ammo creates bubblegum results. I didn't want to take all the blame for the crappy shot groups on my last outing.
    Here is the tool and the play field.
    2eqc8k8.jpg
    2053yif.jpg
    Started with 20 rounds of the SSA (Silver State Armory) 168gr. The bubblegum kept failing to eject amongst other issues. Very disappointing. Here are the results at 50m.
    4py0i1.jpg
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    I then shot 20 rounds of the Federeal Sierra Matchking 168gr at 100m for slightly better results. I had to make an adjustment to my windage after that batch.
    wvwveo.jpg
    You can see the windage adjustment helped when you see the group below.
    2wdbqk9.jpg
    Then I went to what I decided was my favorite for the day. I was creating shot groups of 5 rounds with results like what you see below at 100m with the NORMA USA Sierra Matchking 168gr
    wbuvic.jpg
    I had a lot of fun but I was experiencing more failures today than the last time I shot it with Jukk0o. I had no failures last time. Today I was getting my bolt jammed tighter than bubblegum because it was destroying or extricating the primers altogether. The loose primer shards were getting stuck in the lug area and jamming my bolt face to where it took some good effort to free the BCG and clear the jam. See below.
    2vxm07l.jpg
     
  2. clearconscience

    clearconscience Vancouver, WA Well-Known Member

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    That's a great looking gun.
    I built a ar15 last year and first time out was light striking the primers and failing to set rounds off. Every 4-5 shots was a dud.
    Swapped the JP light hammer spring for the stock spring and was flawless.

    My next buy/build will be an AR10 so I look forward to hearing what your fix is.
     
  3. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    Haha! Great news!! I swapped out the BCM gas block for the Syrac adjustable gas block. I went through the process of firing one round at a time and dilating the gas hole one click at a time with the set screw until I reached the point where the bolt carrier group was locking open on the empty mag. The adjusting screw mechanism on the Syrac gas block is totally cool because you can feel and hear it click at each increment as you adjust it. It makes for a very precise operation. Additionally the Syrac can be adjusted with the hand guard mounted. They supply you with an enlongated allen key to make the adjusting quick and easy.

    Long story short, the AR10 is cycling like a dream and the brass gets ejected at the proper angle looking pristine like it is ready for reloading. No hiccups to report once I got her dialed in.

    Next stop, Geissele DMR installation. I'd be lying if I said I wasn't a little intimidated by this install.
     
  4. Certaindeaf

    Certaindeaf SE Portland Well-Known Member

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    Yea, yer gun is ruined. If you got primers blown like that, a very many bad things have happened to lead up to that point.
     
  5. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    Yeah I planned on throwing it away before someone gets seriously hurt.
     
  6. wedge556

    wedge556 seattle Member

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    Have had similar primer issues. Seemed to be ammo related. Sadly my wee-SASS doesn't like Federal match king. Has no issues with surplus anything. Might have to consider your adjustable gas block solution, thanks!
     
  7. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    I think the adjustable gas block may be just what the doctor ordered for you. It worked miracles for my problem.
     
    Last edited: Jul 5, 2015
  8. Heywood

    Heywood Prineville Oregon Well-Known Member

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    Just from those pictures of your brass, I would guess you have some real pressure issues! With ejector swipes like that and popped primers along with stuck cases. It looks like something serious is goin on...
     
  9. old11bravo

    old11bravo Everett, Washington Well-Known Member

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    All fixed up!
     
  10. Flopsweat

    Flopsweat Slightly right of center Well-Known Member

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    Here, let Bill show you how to install his triggers. They provide a dummy pin too. It will probably take you less time to install the trigger than it does to watch the video. As long as you watch the video. ;)

     
    IronMonster likes this.