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  1. #1
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    Default Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Can anybody help me out with symptoms of short stroking in a semi-auto shotgun?

    I've owned numerous semi-auto handguns and rifles, but never a semi-auto shotgun.

    The gun's a brand new gas operated SDS AR T-02.

    The first time I shot it (with full power buckshot loads of various types) I would generally get a stoppage on the second to last or last round.

    When this happens, the shell stop seems to be disabled, allowing a round to exit the magazine tube, tying up the gun by lying on top of the shell lifter.

    Playing around with snap caps, I noticed a similar behavior unless the bolt handle was FORCEFULLY pulled to the rear.

    I'm thinking that it's possible that the gun is sometimes short stroking, preventing the action from fully cycling. As I said, the gun is new and that model has a reputation for requiring break-in. I've added a +2 magazine tube extension, the spring for which seems excessively long/powerful. While cleaning and lubing the gun, I reinstalled the OEM spring, which seems to work much better in combination with the extension.

    As I've said, I'm new to semi-auto shotguns, having only POSSIBLY shot one once before.

    Any advice would be appreciated.
    Je suis Charles Martel.

  2. #2
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by Deanimator View Post
    Can anybody help me out with symptoms of short stroking in a semi-auto shotgun?

    I've owned numerous semi-auto handguns and rifles, but never a semi-auto shotgun.

    The gun's a brand new gas operated SDS AR T-02.

    The first time I shot it (with full power buckshot loads of various types) I would generally get a stoppage on the second to last or last round.

    When this happens, the shell stop seems to be disabled, allowing a round to exit the magazine tube, tying up the gun by lying on top of the shell lifter.

    Playing around with snap caps, I noticed a similar behavior unless the bolt handle was FORCEFULLY pulled to the rear.

    I'm thinking that it's possible that the gun is sometimes short stroking, preventing the action from fully cycling. As I said, the gun is new and that model has a reputation for requiring break-in. I've added a +2 magazine tube extension, the spring for which seems excessively long/powerful. While cleaning and lubing the gun, I reinstalled the OEM spring, which seems to work much better in combination with the extension.

    As I've said, I'm new to semi-auto shotguns, having only POSSIBLY shot one once before.

    Any advice would be appreciated.
    The magazine spring may be causing the problem. Normally when adding a magazine extension you want about 12-16" of uncompressed spring measuring from the end of the tube to the end of the spring outside of the magazine tube. Start with around 20" and load dummy rounds and see if the tube will take all the rounds it's specified to hold. If it doesn't hold all the rounds cut 2" off the spring at a time and try again until it just takes all the shells. It should be around 16" or so inches. If at least 20" isn't sticking out of the tube and it's much less than 12" then the spring is too short. I use Nordic Accessories springs that come in about 45" lengths.

    https://nordiccomp.com/categories/ex...-tube-springs/

    One other thing to check with the extension tube you added. Make sure the tube of the added extension sits flush with the shotgun stock magazine tube. If there is a gap between the two tubes the spring has a chance of hanging up in the gap reducing the spring tension at the receiver. One piece extensions (nut and tube are all one) are a culprit for this as opposed to a two piece (nut and tube are separate) which you can check and adjust makes a difference.

    Also, I would disassemble it and clean the action and lubricate it with some high quality oil and run the gun again after checking your spring and added extension.
    Corruption is the default behavior of government officials. JPC

  3. #3
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by JenniferG View Post
    The magazine spring may be causing the problem. Normally when adding a magazine extension you want about 12-16" of uncompressed spring measuring from the end of the tube to the end of the spring outside of the magazine tube. Start with around 20" and load dummy rounds and see if the tube will take all the rounds it's specified to hold. If it doesn't hold all the rounds cut 2" off the spring at a time and try again until it just takes all the shells. It should be around 16" or so inches. If at least 20" isn't sticking out of the tube and it's much less than 12" then the spring is too short. I use Nordic Accessories springs that come in about 45" lengths.

    https://nordiccomp.com/categories/ex...-tube-springs/

    One other thing to check with the extension tube you added. Make sure the tube of the added extension sits flush with the shotgun stock magazine tube. If there is a gap between the two tubes the spring has a chance of hanging up in the gap reducing the spring tension at the receiver. One piece extensions (nut and tube are all one) are a culprit for this as opposed to a two piece (nut and tube are separate) which you can check and adjust makes a difference.

    Also, I would disassemble it and clean the action and lubricate it with some high quality oil and run the gun again after checking your spring and added extension.
    Thanks.

    The spring that came with the extension would not allow seven rounds to be loaded. I've reinstalled the OEM spring without modification. The extension fits flush after cutting off a couple of turns on the end of the magazine tube. It wouldn't tighten down on the forend and lock ring beforehand (done before shooting it).

    I cleaned and lubed the gun again before [unsuccessfully] trying to remove the broken rail screw.

    I won't get to test it again until Sunday, after work.
    Je suis Charles Martel.

  4. #4
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    My M3HB used to do that, it would crush the case and render it useless for reloading. It was due to oil on the buffer.
    Yours sounds like your spring needs to be cut.

  5. #5
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by bogey1 View Post
    My M3HB used to do that, it would crush the case and render it useless for reloading. It was due to oil on the buffer.
    Yours sounds like your spring needs to be cut.
    Assuming you mean the magazine spring, I'm going to try the OEM spring, then modify the replacement spring as required.

    Thanks.
    Je suis Charles Martel.

  6. #6
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by Deanimator View Post
    Assuming you mean the magazine spring, I'm going to try the OEM spring, then modify the replacement spring as required.

    Thanks.
    The buffer spring. Short stroking is when the bolt only opens up half way or so.
    If that's the problem, you need a new spring, or mod the existing.
    My black aces tactical has issues like that, they recommend a different spring, or cut it.

    Is that the problem you are having?

  7. #7
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by bogey1 View Post
    The buffer spring. Short stroking is when the bolt only opens up half way or so.
    If that's the problem, you need a new spring, or mod the existing.
    My black aces tactical has issues like that, they recommend a different spring, or cut it.

    Is that the problem you are having?
    What was happening was that the gun would fire, it would eject the empty and a loaded round would come out of the magazine and sit on top of the lifter, tying the gun up.
    Je suis Charles Martel.

  8. #8
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by Deanimator View Post
    What was happening was that the gun would fire, it would eject the empty and a loaded round would come out of the magazine and sit on top of the lifter, tying the gun up.
    I think that was the same problem with the black aces tactical. They recommend a high brass shell, unless you,
    'change or mod the spring. Springs are cheap, try cutting a coil or so at a time to see if it helps.
    I cut one too short once, so I just stretched it out, and it worked
    Sometime us gun owners get too anal with things. Thats when I go full Macgyver.

  9. #9
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    Quote Originally Posted by bogey1 View Post
    I think that was the same problem with the black aces tactical. They recommend a high brass shell, unless you,
    'change or mod the spring. Springs are cheap, try cutting a coil or so at a time to see if it helps.
    I cut one too short once, so I just stretched it out, and it worked
    Sometime us gun owners get too anal with things. Thats when I go full Macgyver.
    I assume you mean the "recoil spring". I'm reluctant to modify that until I know of a source for a replacement, and at this point I don't know of any source for parts for this gun. Perhaps the spring from one of the similar Turkish guns is interchangeable.

    BTW, the bolt release button is EXCEPTIONALLY stiff. You actually have to pull the bolt back to activate it. Is that a sign of a too heavy spring?
    Last edited by Deanimator; November 2nd, 2021 at 10:36 PM.
    Je suis Charles Martel.

  10. #10
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    Default Re: Symptoms of Short Stroking in a Semi-Auto Shotgun?

    I would put the gun back to 100 percent stock and shoot the shit out of it. Does it work in this configuration? If so, shoot the shit out of it some more and "break it in". That way, you are certain that it runs. Then add your tube and see what happens. At least that's where I would go.

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