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Thread: Precision rifle alternating between double feeds and short stroking-Troubleshoot how?

  1. #11
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    Quote Originally Posted by TehLlama View Post
    Figured it out, I think. Carrier key. It's got slop,
    That's it. Carrier keys will tolerate no leakage at all. You start losing gas there, and it's going to be problematic.

    Remove it, clean it up, lap it if possible, seal it, torque it to common sense tight, and stake it.

    (If you don't have the tools or a AR guru near you, you can send the unit to Gunz or I and we'll have it right in no time)
    Last edited by markm; 02-18-14 at 13:38.
    "You people have too much time on your hands." - scottryan

  2. #12
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    Waiting to hear back from the builder, but now that I've cleaned the carbon out from around it, there's even more slop - I'm a bit surprised it ran even intermittently. While I'm waiting to hear back, I'm going to hunt for a better flashlight, and try to make sure that this hasn't galled the upper anywhere, or left anything other than just some odd witness marks on the gas tube.
    عندما تصبح الأسلحة محظورة, قد يملكون حظرون عندهم فقط
    کله چی سلاح منع شوی دی، یوازي غلوونکۍ یی به درلود
    Semper Fi
    "Being able to do the basics, on demand, takes practice. " - Sinister

  3. #13
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    Yeah. I had a key bolt snap. The key still felt tight, but if you looked close there was a slight gap under the front of the key. That small leak was all the difference in the world. I even had Specialized Armament look at it, and they said it was fine. Went home and pulled it apart myself.
    "You people have too much time on your hands." - scottryan

  4. #14
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    Quote Originally Posted by TehLlama View Post
    16" Douglas barrel, Midlength gas, Pinned LP gas block (I can't visually see any signs of a gas leak) Young MFG BCG - though it's quite solidly staked. The thought occurs to me that I had the lower with a slightly odd buffer/spring combination when I tried the other BCG, so I'll take a closer look at that, might still be the BCG.

    I'm confident it's short stroking because it started failing to lock back on the last round with every magazine I've thrown at it, and while it's a pretty heavy barrel with a brake affixed, I'm not feeling the buffer reach the back of the stock, and I've had a few FTF cases where it has picked up a round from the magazine but lacked momentum to finish chambering the round. I did run the H2/Blue combo to be more confident it wasn't just outrunning the mag spring, but I'm fairly sure it's just too little input energy.

    At such a low round count, with all brand new hardware, I'm not sure how anything wouldn't be an assembly issue, so I'll give it one more look over.
    I would first check the GB placement over GP and while you are at it, measure the GP size. Inspect the GT and make sure that everything looks ok. If everything checks out, I would try a better quality BCG.

    When troubleshooting short stroking, I always narrow down the variables by using 5.56 pressured ammo AND use a car buffer with a standard USGI spring.


    Edited, never mind my post. LOL.

    C4
    Last edited by C4IGrant; 02-18-14 at 14:20.

  5. #15
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    Take that Youngs BCG, sell it and get a real one. If you are really set on it, then remove the key, get a quality one from BCM (it comes with screws). Apply some red Loctite to the screws and then tighten them down. Have someone stake it with a MOACKS.

    Quote Originally Posted by TehLlama View Post
    Waiting to hear back from the builder, but now that I've cleaned the carbon out from around it, there's even more slop - I'm a bit surprised it ran even intermittently. While I'm waiting to hear back, I'm going to hunt for a better flashlight, and try to make sure that this hasn't galled the upper anywhere, or left anything other than just some odd witness marks on the gas tube.



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  6. #16
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    That's a good point. If the assembler didn't get the fasteners tight, who knows what key and bolts he put on the unit. Might as well get BCM checked parts.

    Pappabear runs a few of the Young Carriers and they work. They were just a tad tight in the beginning. On a serious gun, I like to stick to a standard Colt or BCM BCG for sure though.
    "You people have too much time on your hands." - scottryan

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