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Thread: BCG binding after firing PA-10

  1. #1
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    BCG binding after firing PA-10

    I have a PSA gen2 upper and lower PA-10 with a Faxon barrel and Ballistic Advantage BCG. The receiver extension & buffer is PSA's PA-10 version. I fired for the first time this weekend and got about 2 rounds off before the BCG stuck to the rear, locked open. It is binding on something, but I can't tell exactly what. Its not the Bolt catch, as you can see in the pics, its a good bit further back to the rear and the catch isn't coming into contact at all. I disassembled everything to see if there were any noticeable wear marks anywhere, and say some strange marks on the threads on the receiver, but nothing corresponding on the BCG.

    Any ideas on where to start troubleshooting? Im stumped here....





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  2. #2
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    Weird ... what about removing the buffer tube off of the receiver?
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  3. #3
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    Don't be surprised if you have a blown primer somewhere that is potentially lodged between the upper and BCG. I also seeing something strange in Pic 1 at about 1:30.



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  4. #4
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    Here is my wild guess. It is hard to tell from the picture, but in the pic of your lower receiver, the threads look destroyed in two spots. The spots look white like bare aluminum. And there appears to be a white powder nearby. Is the carrier hitting those two spots? If the carrier is traveling too far back maybe that would cause the bearing surfaces of the carrier to hit the threads in that location and bind. I'm not familiar enough with ar-10's to know if this is possible before the gas key would hit the lower. If this is happening maybe your buffer is too short.

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  5. #5
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    This was is EXACTLY. The carrier was the stubby Pa-10 version (I'm guessing for use maybe if it is a 5.56 tube) and when I took the spring out, you could see that the BCG was wedging into the threads. I swapped a standard buffer out of one of my 5.56 guns and it's cycling fine now. The buffer was too short. Thanks guys!

  6. #6
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    The best option is to use the Vltor A5 tube and then a standard USGI styled buffer like an H2 or H3. That of course depends on how it was ported.

    Quote Originally Posted by RedRallyeZ View Post
    This was is EXACTLY. The carrier was the stubby Pa-10 version (I'm guessing for use maybe if it is a 5.56 tube) and when I took the spring out, you could see that the BCG was wedging into the threads. I swapped a standard buffer out of one of my 5.56 guns and it's cycling fine now. The buffer was too short. Thanks guys!



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  7. #7
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    Good catch. It was hard to tell with the glare of that pic.

    Quote Originally Posted by P2000 View Post
    Here is my wild guess. It is hard to tell from the picture, but in the pic of your lower receiver, the threads look destroyed in two spots. The spots look white like bare aluminum. And there appears to be a white powder nearby. Is the carrier hitting those two spots? If the carrier is traveling too far back maybe that would cause the bearing surfaces of the carrier to hit the threads in that location and bind. I'm not familiar enough with ar-10's to know if this is possible before the gas key would hit the lower. If this is happening maybe your buffer is too short.

    Sent from my XT1565 using Tapatalk



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  8. #8
    FaxonNathan Guest
    Overtravel is the most common thing we have seen with customer's builds. Couple of quarters to the back of the buffer tube solves it quickly.

  9. #9
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    Yes, agree with over-travel. Surprisingly the quarter trick works very well. Have had this happen before for with a previous build.

    +1 on the A5 buffer tube and the H3 buffer for an optimal carbine setup.

    The other problem with too much over travel is that it is really hard on the bolt catch... As the bolt slams forward, the larger 308 BCG mass along with a stronger buffer spring place ALOT of load on it. I figured this out only after the failure of 2 bolt catches.

  10. #10
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    Quote Originally Posted by FaxonNathan View Post
    Overtravel is the most common thing we have seen with customer's builds. Couple of quarters to the back of the buffer tube solves it quickly.
    How amazing! This is rarely seen when a manufacture mentions .25 cent quarters since the early 9mm AR days.

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