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Thread: Sheared extractor

  1. #1
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    Sheared extractor

    Saw an AR tonight that sheared off not one but two extractors. AR was a Rock River, marked 5.56 but presumably actually .223, owned by a good shooter and shot quite bit. Had a malfunction, turned out to be a sheared extractor. Borrowed a BCG from another shooter and did the same thing to that extractor. Borrowed BCG had a BCM extractor.

    The shooter is going to go home and clean it, and come back next week so we can drop Ned's .223/5.56 gauge in the chamber and see what's what.

    Any other thoughts?

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    Rob,

    Can you post some pics? Two in one day is just crazy. What type of ammo was he shooting? My guess is that thing is really tight.

    Quote Originally Posted by rob_s View Post
    Saw an AR tonight that sheared off not one but two extractors. AR was a Rock River, marked 5.56 but presumably actually .223, owned by a good shooter and shot quite bit. Had a malfunction, turned out to be a sheared extractor. Borrowed a BCG from another shooter and did the same thing to that extractor. Borrowed BCG had a BCM extractor.

    The shooter is going to go home and clean it, and come back next week so we can drop Ned's .223/5.56 gauge in the chamber and see what's what.

    Any other thoughts?



    Owner/Instructor at Semper Paratus Arms

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

  3. #3
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    I wanted to add that the loaned BCG is mine. It is from BCM, and ran like a top in the LMT 10.5" upper that I got from them too. I have about 3K through my 10.5" gun. Lube it generously and shoot Factory Xm193 or Hornady TAP 60 gr.

    I do not know what ammo the other guy was using, but as Rob stated above this guy is a good shooter and shhots quite a bit with this gun.

    I could not tell what was happening. But, I will be calling BCM to order a new extractor or two or three tomorrow.

    ANY input or ways to make sure this stops is appreciated.

    I think Rob got some pics of the extractors...

    Jack
    Colt AR-15/M-16 Armorer, GLock Armorer, HK USP Armorer
    Firearms Instructor

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    I'll post pics later today assuming they come out.

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    It also sounds to me like a tight chamber. I find that the reamer will always remove material from RRA barrels. The RRA owner might also want to use an H or H2 buffer to slow bolt velocity down.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Robb, any thoughts on why the problem would just show up now, and when it did show up it appears to be chronic? this guy shoots with us a lot, does the matches and the drills, has taken at least one class maybe more from jackinfl, and AFAIk it's all been with this carbine with that BCG. If it had only happened to his original extractor I would have just chalked it up to being worn out, but to do it to another right after it makes me wonder if something in the gun hasn't changed to cause it to shear extractors.

    Tuesday I'll drop the checker into it, and we'll verify ammo used, buffer, and we'll replace it with a brand new BCM extractor and see if it still has the same problems. I'll also bring a couple of other buffers so we can swap his out.
    Last edited by rob_s; 07-29-09 at 07:24.

  7. #7
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    pics, which are not so great. Tried to show the pics unretouched and with a red line indicating the shear point. Pics of second extractor didn't come out so good and don't really show anything. I'll try to swap Jack a new BCM for his sheared one.








  8. #8
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    I'm thinking the gas port may have eroded open enough (and RRA are already pretty big) to cause this gun to cycle too fast and might be causing this.
    If you can easily remove the gas block or FSB check the size of the gas port.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  9. #9
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    I was kind of wondering that myself. Especially if he has put lots of rounds through it like Rob says. Combine that with a potentially tight chamber (pretty sure the RRA ones are not true 5.56) and I can see how it would happen. I would be tempted to try an H2 buffer to see what happens for S&G.

    Quote Originally Posted by gotm4 View Post
    I'm thinking the gas port may have eroded open enough (and RRA are already pretty big) to cause this gun to cycle too fast and might be causing this.
    If you can easily remove the gas block or FSB check the size of the gas port.



    Owner/Instructor at Semper Paratus Arms

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

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

  10. #10
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    How is the gas port measured? Interior dimensions with the dial caliper? What are the szie ranges for "in spec"?

    By the way I asked the shooter how many rounds and he said 120K. But this was a quick off the cuff comment... I have known him for a few years and this is the gun he uses.

    One point, but I do not think it is directly related tot he extractor, but a year ago at a class upon inspecting his gun I found that his ejector had very litttle spring tension. I pulled it out and the spring was broken in two pieces.

    Jack
    Colt AR-15/M-16 Armorer, GLock Armorer, HK USP Armorer
    Firearms Instructor

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