Need advice

Discussion in 'Gunsmithing Forum' started by txmadelatino, Feb 19, 2011.

  1. txmadelatino

    txmadelatino New Member

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    I have recently purchased a Bushmaster XM15-E2S from a local FFL dealer. I am having some issues with it missfeeding and locking after emptying the magazine. This is what I have done so far.

    1. i've tried replacing the magazines from the standard military issue mags to a PMAG. Still doing it.

    2. I've tightened the magazine catch. Still doing it.

    3. I've checked the bolt gas rings to insure they are 120degree offset from each other. Still doing it.

    4. I've lubed the bolt and bolt carrier and all inside correctly. Still doing it.

    I allowed one of the knowledgeable FFl dealers to inspect it and they said it might be the ramp on the star chamber is to rough and needs to be polished. Nearest gunsmith wont be in till next week. any other ideas on what could it be before i spend money on it getting fixed?
     
  2. Sniper03

    Sniper03 Supporting Member Supporter

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    Is the Carrier Key on the Bolt Carrier tight? Is it used or new?

    03
     

  3. txmadelatino

    txmadelatino New Member

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    used

    I bought the weapon used from the dealer.

    yes the carrier key is on tight.
     
  4. Sniper03

    Sniper03 Supporting Member Supporter

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    TX

    As you know it is hard without seeing the rifle. Just as a wild guess you might check the carrier key inside to see if someone might have cleaned it with a Q-Tip and got some inside. Believe it or not it happens and then when the gun is fired the cotton material turns black and you can not hardly see it. Obviously you must have just got the rifle. And if you did it probably had that problem is the reason they traded it in unfortunately. But I hope that was not the case. If you just got it I would go back to the dealer for repair on him or your money back. There are a multitude of things if could be. When you put an empty magazine in and pull the charging handle back will the bolt carrier lock back? I will stay here with you on the Forum!
     
  5. Sniper03

    Sniper03 Supporting Member Supporter

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    One other quick check TX!

    Take the Bolt Carrier out. Pull the Bolt out to its furthest extended position. Then set it with the Bolt on a flat surface with the Bolt Carrier in a Vertical position. If the Carrier falls down on the Bolt you may have a Gas Ring problem? Also check the strength of the Ejector by pushing it in and out. Then the Extractor by pushing it outward. If either seem weak that would certainly cause the problem with the ejection but should not cause the Bolt to not lock back.
     
  6. txmadelatino

    txmadelatino New Member

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    Yes the bolt carrier locks back.
     

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  7. txmadelatino

    txmadelatino New Member

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    pictures continued of chamber
     

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  8. txmadelatino

    txmadelatino New Member

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    both ejector and extractor have great strength when i apply pressure.
     

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  9. Sniper03

    Sniper03 Supporting Member Supporter

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    Looking at the pictures:
    1. Have you tore the Bolt Carrier down all the way and cleaned the carbon off the tail shaft of the Bolt
    2. Be sure the Locking Lug area of the Barrel Extension is clean where the feed ramps are and inside behind them. It seems like I see some brass?
    3. But it may be deceiving iin the picture but the Carrier Key just does not look right in the picture. Is it jagged and not uniform around the Carrier Key hole as it looks?
    Which brings me to the point if it is damaged it has in all probability worn the Gas Tube end that is supposed to have a flared end on it. If you could send a better picture of the Carrier Key and Gas tube inside that would be helpful.

    03
     
  10. Sniper03

    Sniper03 Supporting Member Supporter

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    I missed the most simple question! Have you tried ohter magazines?
     
  11. txmadelatino

    txmadelatino New Member

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    yes i have tried the military issued mags. and i upgraded to PMAGS today at the range and the FFl dealer even tried different ones they had in the shop..still did it. im breaking down the bolt system now.
     
  12. Gatekeeper

    Gatekeeper New Member

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    Thats what i was thinking, it might just be the angle or lighting of the pic but the nose of the carrier key looks short and worn down, might not be sealing with the gas tube
     
  13. txmadelatino

    txmadelatino New Member

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    more pics of bolt
     

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  14. txmadelatino

    txmadelatino New Member

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  15. Sniper03

    Sniper03 Supporting Member Supporter

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    Tx

    The Extractor Insert should have a spring over it. It also looks like the large head of the insert is upside down in the picture. It should be installed by sitting down the Insert like it is a nail on a flat surface with the large head sitting on the flat surface. Then the Extractor Insert Spring has a large coil on one end and a smaller coil on the other. When the Spring is placed over the Insert the Large Coil should be down against the large head on the insert. The the Large Coil of the Spring and the large head of the Insert go down into the Extractor Indentation recess. You Can pinch it in gently until it snaps into place. Is there even a Spring on the Blue Insert? Can't see one in the picture. Also I will be sending you a PM in a minute. We may have found your problem?

    03
     
  16. txmadelatino

    txmadelatino New Member

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    here they are
     

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  17. txmadelatino

    txmadelatino New Member

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    yes the extractor insert is big head down and the small spring in previous pics is the one that goes to that.
     
  18. Wenonah

    Wenonah New Member

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    First, contstructive criticism:
    I'm no AR expert but I can tell you that as difficult as it is to diagnose malfunctions via photographs, blurry photos make it almost impossible. Try laying the carrier key on a white background and make sure the image is crisp before you post it. Play with different lighting angles also to make sure you have good contrast on the critical parts. A shot of the gas tube might be useful as well since it's the seal between the two that gives sufficient energy to the bolt to get a full stroke.

    Now questions:
    By miss-feed do you mean that the round is not moving smoothly into the chamber or is the bolt failing to catch it at all leaving it in the magazine while the bolt closes on an empty chamber? If I recall my M-16 days correctly the bolt catch holds the bolt very near the rear of its travel. If it's not stripping a round at all and doing it frequently with multiple mags while not locking back it's apparent that the bolt is not moving to it's full rearward position.

    Theory:
    If, as you say, everything is clean, lubed and moves freely without burrs then the problem is likely in the gas system. Clean the tube and make sure there is a good seal between the tube and carrier key. Obstructions or excessive leakage can both reduce energy transmitted to the bolt carrier and cause short strokes which would lead to a failure to eject, failure to lock back and cause the bolt to close on an empty chamber with rounds in the mag. It sounds like you may need a new gas tube and/or carrier key to get this thing running properly.

    My opinion on the roles people play:
    Firearms dealers are not necessarily experts in firearms, they are experts in sales and the administrative requirements to commercially sell firearms. Most firearms dealers are interested in firearms while other guys, like you'll find in the gunsmith forums, are interested not only in firearms but how they work; you came to the right place.
     
    Last edited: Feb 19, 2011
  19. Wenonah

    Wenonah New Member

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    As an afterthough, don't forget to disassemble and clean the recoil spring in the butstock. Grit in there is harder to feel but can rob enough energy to cause the same issues.
     
  20. JonM

    JonM Moderator

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    couple of things.

    what ammo are you using?? some foriegn ammo can be underpowered or over powered.

    the barrel extension looks boogered up. like the previous owner tried to dremel m4 cuts. i would also check to mke sure the barrel is on tight enough and the front gas block is centered.

    can also remove the gasblock and check for fouling in the front end parts and run a really long pipe cleaner through the tube. check to see if gas is leaking around the gas port. look for a LOT of dirt around the port area.

    incorrect buffer spring can cause feed issues as can a worn buffer retaining detent.

    a heavier than spec buffer can also cause it.