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Thread: Geissele short stroking????

  1. #1
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    Geissele short stroking????

    I have a brand new Geissele SDP, 11.5", 556mm/DDC in May of this year....NO Mods...put some new ammo(can't remember the brand name), on the magpul mag and when out shots some ~100 rounds at the range. Got home put away without cleaning or lube. Last Monday, taken the AR out to the range and shots few round but this time it wouldn't cycle so I'd manually feed the next ammo by using the charging handle,...I'd change the new mag and still doesn't function correctly. So on the next day, I'd cleaned out upperrecevier; BCG, bolt, rail, barrel, charging handle, buffer, buffer spring....and lubed! I'd taken out to the range and 1st shot fired and it would cycle the 2nd round and fired but the 3rd round would jammed by the bolt and pushed it up against the upper bolt chamber and the 4th ammo would pinned underneath the 3rd ammo!!!! does this makes any sense??!!

    any ideas what is world going with my baby?? This is more than $2200.00!! I should've gotten the DD/MK18!!! The tech guy from Geissele suppose to call me today.


    HELP

  2. #2
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    Sounds like a gas issue.

    Check your gas tube to ensure it isn’t clogged up.
    Also make sure the gas block is still in place and tight.
    Then go through your BCG.

  3. #3
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    Thanks "lonestardiver"....I just got off the phone with Geiessele tech guy... he said I should run the different type of ammo's & mag and re-run the test and take a few pic's of each ammo's & mag and send the pic's to them if I problems continue. This driving me NUTS!!!!

  4. #4
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    I have seen a gas block shift to where it is just enough off center of the gas port to impair function.

    Different ammo based on powder type also changes the pressure curve which can also affect things. Go back to the same ammo you tried at first when you did not have any issues. That being a known quantity can be an important fact.

  5. #5
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    The ammo is same ammo & Magpul mag that I used on 1st & 2nd test runs.

  6. #6
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    Look under or through the rail to see if the gas block has shifted forward or to the side. An 1/8” of an inch forward shift can cause issues in some uppers.

  7. #7
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    If I understand you correctly, the third round fires, the action cycles but the third round does NOT eject. The bolt picks up the fourth round and the AR is jammed with the third (fired) round and the fourth (live) round.

    AR might be short stroking. The only way to check that is to do a lock back check- that is, place a single round in the magazine, load the rifle and see if it locks back.

    But the AR definitely has a failure to eject. We know this because the only way the bolt can travel far enough to push a round from a good mag is if the bolt passes the point where the empty is ejected. In its reward travel, the bolt passes the point of ejection before it reaches the point it can strip a round from the mag.

    The most common cause of failure to eject in an AR is a failure of the extractor. Not only must the extractor pull the round from the chamber, it must also hold the case tight against the bolt face to compress the ejector. If the ejector isn’t fully compressed, it cannot apply its full force to the extracted round. Extractor springs fail far more often than ejector springs.

    Start with installing a new Colt extractor spring, then perform a lock back check. Perform tests using MagPul Gen III mag to remove as many magazine induced variables as possible.
    Last edited by MistWolf; 09-16-21 at 13:57.
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

    http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0114.jpg
    I am American

  8. #8
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    Thanks for the feedback MistWolf....1st round fired and cycle the 2nd round into the chamber and cycle out...BUT the 3rd round jammed at the top and bolt pressed against the 3rd and same time the 4th round pinned under the 3rd.... i'd know, it confusing without the pic's!!! This happened 2 or 3 times in the roll!!! I'd had to released the mag and removed the jammed ammo's(3rd & 4th) from the chamber
    Last edited by Jamessdp115; 09-16-21 at 14:35. Reason: more info...

  9. #9
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    Quote Originally Posted by Jamessdp115 View Post
    Thanks for the feedback MistWolf....1st round fired and cycle the 2nd round into the chamber and cycle out...BUT the 3rd round jammed at the top and bolt pressed against the 3rd and same time the 4th round pinned under the 3rd.... i'd know, it confusing without the pic's!!! This happened 2 or 3 times in the roll!!! I'd had to released the mag and removed the jammed ammo's(3rd & 4th) from the chamber
    I think I'm getting the picture.

    Start by installing a new Colt extractor spring. If you can't find a Colt spring, install the Sprinco extractor spring. No O ring. Don't bother with any other brand extractor spring.
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

    http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0114.jpg
    I am American

  10. #10
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    Hmmmm... Why would the brand new Geiessel AR extractor spring goes WRONG??

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