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Thread: Malfunction diagnosis help

  1. #11
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    Quote Originally Posted by mtdawg169 View Post
    IG, thanks for checking in. I have experienced short stroking issues with this ammo before in a different gun. No issues in this rifle with any other ammo, including federal xm193, m855, several flavors of Hornady & Black Hills, Guat m193, TAP practice, ae223 & pmc.

    Looking more closely at that picture now, i'm wondering if the aimpoint cap may have caused an obstruction?
    While the Aimpoint cap may have contributed to the malfunction, my first thought is it's an ammo issue like IG mentioned. I would move the cap and run some good ammo through the rifle and see if you have any other problems.

    You can also examine the extractor and compare the spring to a new extractor spring to make sure it's not worn out.

  2. #12
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    Quote Originally Posted by big b View Post
    While the Aimpoint cap may have contributed to the malfunction, my first thought is it's an ammo issue like IG mentioned. I would move the cap and run some good ammo through the rifle and see if you have any other problems.

    You can also examine the extractor and compare the spring to a new extractor spring to make sure it's not worn out.
    I will try it with different ammo to see if anything else manifests. This carbine has never had an issue in approx. 3k rounds. The centurion ammo has caused bolt over base / sort stroke malfunctions in another SR15 of mine. I just noticed the aimpoint caps after posting this picture. I recently swapped out the T1 mount from an ADM unit. Previously, the caps didn't ride quite so low when stored around the mount base.

    Regarding clearance of the malfunction, TRB almost made it worse. Once I retracted the CH, it would no longer travel back all the way forward as the stovepipe case was in the way. The bolt sandwiced both cases in between the bolt face & the barrel extension.

  3. #13
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    Testing for short stroke would be the first logical step. Load a single round and verify the bolt catch is holding the bolt back after the round is fired.

    If that checks out okay, I would detail strip and clean the bolt, paying attention to the ejector channel, which can occasionally become obstructed with debris. Check the ejector spring and ejector for unusual wear/damage. Make sure the extractor lip isn't rounded off. Check the extractor spring. Be sure it isn't soft, or an older rifle extractor spring with a blue insert. If in doubt, get a new proper carbine extractor spring (with black insert) such as a Colt, BCM or Wolff.

  4. #14
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    Quote Originally Posted by Eric View Post
    Testing for short stroke would be the first logical step. Load a single round and verify the bolt catch is holding the bolt back after the round is fired.

    If that checks out okay, I would detail strip and clean the bolt, paying attention to the ejector channel, which can occasionally become obstructed with debris. Check the ejector spring and ejector for unusual wear/damage. Make sure the extractor lip isn't rounded off. Check the extractor spring. Be sure it isn't soft, or an older rifle extractor spring with a blue insert. If in doubt, get a new proper carbine extractor spring (with black insert) such as a Colt, BCM or Wolff.
    Extractor & ejector check out fine & there were no other issues that day with that ammo. However, it has always exhibited weak ejection. I'm chalking this up to ammo for now unless I start seeing a more consistent problem. I've only got about 200 rounds of that ammo left, so I'll shoot it up and watch for issues with better ammo.

  5. #15
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    aimpoint cap shouldnt be there, asking for a malfunction with anything obstructing the ejection port.
    Last edited by ForTehNguyen; 01-04-12 at 14:19.

  6. #16
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    Out of curiosity what is your barrel length, (carbine or middy), Buffer weight and action spring type? Is your extractor spring a 3, 4, or 5 coil? Do you use an "O" ring (I use a 5 coil and no "O" ring").

    Also what magazines do you use?

    The only time I have had short strokes was when I had cheaper HSM .223 ammo an H2 and Blue tactical spring in my 6920.

  7. #17
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    I am about 99% certain if you stop using that ammo, you will not have issues. If you are using M855, M193 or other known ammo and it happens, then yes there is another issue here.

    Quote Originally Posted by mtdawg169 View Post
    Extractor & ejector check out fine & there were no other issues that day with that ammo. However, it has always exhibited weak ejection. I'm chalking this up to ammo for now unless I start seeing a more consistent problem. I've only got about 200 rounds of that ammo left, so I'll shoot it up and watch for issues with better ammo.



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  8. #18
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    Quote Originally Posted by TacMedic556 View Post
    Out of curiosity what is your barrel length, (carbine or middy), Buffer weight and action spring type? Is your extractor spring a 3, 4, or 5 coil? Do you use an "O" ring (I use a 5 coil and no "O" ring").

    Also what magazines do you use?

    The only time I have had short strokes was when I had cheaper HSM .223 ammo an H2 and Blue tactical spring in my 6920.
    The rifle is a complete SR15 with E3 bolt, standard usgi buffer spring and h buffer. There's no crazy buffer & wonder spring experimentation going on here. I'm chalking this one up to my initial theory of it being an ammo issue unless it starts happening again.

    What i'm curious about at this point is the proper method to clear such a malfunction. Should remedial action usually clear it or is stripping the mag the only way this could be resolved? Maybe someone can point me to a good thread on malfunction types and clearing methods?

  9. #19
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    Quote Originally Posted by ForTehNguyen View Post
    aimpoint cap shouldnt be there, asking for a malfunction with anything obstructing the ejection port.
    This^ there was another thread somewhere same issue.

  10. #20
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    Quote Originally Posted by mtdawg169 View Post
    The rifle is a complete SR15 with E3 bolt, standard usgi buffer spring and h buffer. There's no crazy buffer & wonder spring experimentation going on here. I'm chalking this one up to my initial theory of it being an ammo issue unless it starts happening again.

    What i'm curious about at this point is the proper method to clear such a malfunction. Should remedial action usually clear it or is stripping the mag the only way this could be resolved? Maybe someone can point me to a good thread on malfunction types and clearing methods?



    You have already been given this information and from more than one person. Next range trip why don't you experiment yourself.

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