Short stroking?

Discussion in 'AR-15 Discussion' started by SkilletFan24, Jan 26, 2014.

  1. SkilletFan24

    SkilletFan24 New Member

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    So I shot my AR some more on Friday. I started rapid firing it but it would quickly jam. Slow shots were fine... But as soon as I started shooting quickly it had problems. Now normally my ar doesn't spit the empty casings too far from the ar. I've described it as lazy before, like it doesn't really want to spit them out but it does. They go maybe 3-5 feet from my ar. I didn't think that was a problem but then id fire off like 3 shots before the bolt would lock open with ammo still in the mag. Id have to use the bolt catch to drop the bolt. Does anyone know why this is? Doesn't happen unless I rapid fire.
    Is it possible my rifle is short stroking?
    Also I've used 2 different brands of ammo and it ejects both the same. It's also a new rifle with <100 rounds through it. Maybe 70 or 80 max have been out through it
     
    Last edited: Jan 26, 2014
  2. JonM

    JonM Moderator

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    Pics would help. Mainly looking for type of ar15. Build specs. What buffer spring etc.

    Common mistakes are using a rifle buffer in a carbine build. Using rifle recoil springs in a carbine build. Misaligning the gasblock so it restricts gas flow, misaligning barrel nut so it binds the bcg.. Those are the common issues associated with the symptoms described.
     

  3. SkilletFan24

    SkilletFan24 New Member

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    I'll get some pictures up in a few minutes when I get a chance
     
  4. SSGN_Doc

    SSGN_Doc Well-Known Member

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    Which two types of ammo?
     
  5. JonM

    JonM Moderator

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    Pics of the buffer and buffer spring and stock, good close up of the gas block good close up of the inside of the upper at the gas tube entry point.
     
  6. Mercator

    Mercator New Member

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    Try to get a sharp close-up of the bolt face.
     
  7. DrFootball

    DrFootball disappointed & disgusted, But DETERMINED... Lifetime Supporter

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    and are the casings coming out Damaged??
     
  8. SkilletFan24

    SkilletFan24 New Member

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    ImageUploadedByFirearms Talk1390794063.616887.jpg ImageUploadedByFirearms Talk1390794086.624757.jpg ImageUploadedByFirearms Talk1390794104.521119.jpg ImageUploadedByFirearms Talk1390794133.522469.jpg ImageUploadedByFirearms Talk1390794177.441205.jpg
    The ammo was some Federal stuff (I think) it was brass cases in a black box with a white eagle on it. And some Tula. Both shot fine but I only tried rapid with wolf. Both ejected the same shooting slow.
    I included a picture of the side of my bcg because the retaining ion protrudes just a bit. Not a whole lot but you can feel it if you run your finger along the side of the bcg. I don't know if that's a problem.

    The cases come out fine, although there are some scrape marks along the side of it. Not really deep but I doubt I could buff it out. They'd probably stay after cleaning up the brass/steel.
     
    Last edited: Jan 26, 2014
  9. JonM

    JonM Moderator

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    HArd to tell but the fsb looks canted. Anyway to get a pic from above of the gas system fsb and barrel nut

    Need close up pics of the screws of your gas key on the bolt carrier and where the gas key attaches to the carrier.

    Forgot to add other issues can be worn or damaged gas rings or loose gas key.

    To test the rings extend the bolt out all the way and stand it on the bolt face, if the bolt retracts into the carrier under its own weight your rings are worn and need replacing. Worn/damaged rings also cause cycle issues
     
    Last edited: Jan 26, 2014
  10. SkilletFan24

    SkilletFan24 New Member

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    ImageUploadedByFirearms Talk1390794982.242202.jpg
    The gas keys are good, the bolt stays extended.

    I built my AR from a kit so the bcg didn't come staked. I put loctite on the screws instead and they're locked in place. May as well be staked.
    I also thought my fsb looked canted too, but I wasn't sure.
     
    Last edited: Jan 26, 2014
  11. JonM

    JonM Moderator

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    Loctite might be an issue as it should never be used on the gaskey or its screws it just evaporates under heat leaving things loose if any migrated. I would suggest removing the key clean out all the loctite make sure the mating surfaces of the key and carrier are squeeky clean then retorque to 60 inch pounds front screw then the rear and stake in place. Make sure your not using a gasket compound or sealer of any sort and no loctite.
     
  12. SkilletFan24

    SkilletFan24 New Member

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    Ok I'll do that. But I don't see how that could be why my AR is short stroking?
     
  13. JonM

    JonM Moderator

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    Gaskey screws get loctited, key gets hot, loctite hits crit temp which is very low burns off and screws loosen under recoil allowing gas to escape out the sides. Doesnt take much to start cycle issues.

    Its a cheap fix since its free to do other than elbow grease. That's why proper torque and staking are important.

    Reason I'm leaning this way is the condition of your bolt says its been shot a lot and until recently you have been happy with it until its started giving issues gradually. Since it passes the standing test and the tube looks ok I'm leaning gaskey

    You do have a inch pound wrench??
     
    Last edited: Jan 26, 2014
  14. JonM

    JonM Moderator

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    One other thing. The gaskey is the reverse of the ak design. Stoner took the piston and put it on the rear end of the gas system instead of the front giving the gas time to cool before hitting a piston which is why ar15/m16 run longer with a higher sustained fire than ak47 m1a m1 garand m1 carbine sks or other moving piston guns. But it also means the pressure is lower so any leaking at all means you get cycling issues.
     
  15. SkilletFan24

    SkilletFan24 New Member

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    Yes I do.
    I've only put maybe 80 rounds through it, no idea about who may have had it before me. The screws haven't changed at all though, so I'm kinda doubtful it's them. I'll still listen to your advice though. Thanks for your continues help.
    I think tomorrow I am going to take a closer look at the fsb and see if it's canted. It could very well be a few degrees off. If it's not that then I have no idea what it could be ._.
     
  16. JonM

    JonM Moderator

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    I would redo the key first it really helps a lot when its right. I've rebuilt several dpms and bushmaster bcg for friends who have had cycling issues and just getting everything clean torqued and staked does wonders. Not saying its THE issue but its definately not right looking at the pic. Maybe why the previous owner sold it.

    The screws can be loose and let gas leak but still feel and look tight. The wiggle test doesn't work in this case
     
  17. SkilletFan24

    SkilletFan24 New Member

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    Ok, I'll work on it. Guess that's all I can do for now. I'll see if that fixes it. Thanks again for the help, I appreciate it!
     
  18. JonM

    JonM Moderator

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    Good luck. Its an easy free place to start and I think might be the issue. Let us know what happens.
     
  19. SkilletFan24

    SkilletFan24 New Member

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    I'll be sure to give an update as soon as I can take it to the range.