AR15 trigger

Discussion in 'AR-15 Discussion' started by Bob T, Nov 30, 2019.

  1. Bob T

    Bob T New Member

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    DPMS complete lower kit, Mil collapsible stock with carbine buffer/spring: When single loading, the round fires and shell extracts correctly, but the trigger doesn't always reset. When this happens with a full magazine, it results in auto discharge. Is this a timing mismatch between the trigger and buffer springs?
     
  2. Gatoragn

    Gatoragn Well-Known Member Supporter

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    If the bolt cycles enough to chamber another round, it should be resetting the trigger. Something is defective. Is the trigger stock or has it been "tuned"?

    If this is a new lower purchased complete, I would contact DPMS customer service.

    If not new, I would obtain and install a new trigger.
     
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  3. Sniper03

    Sniper03 Supporting Member Supporter

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    Bob
    Sound like to me you either have tolerance problem between the Trigger Group and the Carrier or a Disconnector issue.

    But first make sure the Disconnector Spring is in the Trigger correctly. The larger of the two coils goes down in the Trigger Box first. If it is in incorrectly (Upside down) it will not allow the Disconnector to go down far enough to grab and hold onto the rear of the Hammer. Therefore allowing the Hammer to not reset.

    The other thing is if you can, see if you can get another trigger and hammer to try in the Receiver. Lately I have seen those that the tolerances are off between the Receiver, the Carrier and the Trigger and Hammer Group. Causing exactly the issue you mentioned.

    Are all the parts and receiver from DPMS?

    03
     
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  4. primer1

    primer1 Well-Known Member Supporter

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    Welcome to the forum, Bob. There is lots of good people here with an endless amount of answers and information. Stop by the introductions when you get a chance.
     
  5. locutus

    locutus Well-Known Member Supporter

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    An aftermarket trigger, like a Giessele is always a good investment for an AR.
     
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  6. Caveman Jim

    Caveman Jim Well-Known Member Supporter

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    I second the "send the lower back", definitely an out of spec disconnector or FCG.
     
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  7. armoredman

    armoredman Well-Known Member

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    Home built or factory? That's the most important question.
     
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  8. Bob T

    Bob T New Member

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    The receiver is not DPMS, just the parts. I'll look at it further. Thank you.
     
  9. Bob T

    Bob T New Member

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    I was looking at them. I might give them a try.
     
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  10. JTJ

    JTJ Well-Known Member Supporter

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    I had my DPMS parts lower go binary. I dont think the trigger group was properly heat treated and wore prematurely or something is out of tolerance. I replaced the trigger assembly with a JMT drop in for under $100 and got a nice 3 lb trigger. Much better than the DPMS.
    https://wildsavagedeals.com/product...e-drop-in-trigger-anti-rotation-pins-included
    Optics Planet has the Rise 140 Drop In for $84.99 with 11% off code BLACK.
    https://www.opticsplanet.com/rise-armament-ra-150-super-sporting-trigger.html
     
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  11. Sniper03

    Sniper03 Supporting Member Supporter

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    If you shop around you can get a Rock River National Match Trigger Group for around $100.
    They can not be beat for the quality and the money!
    But I do not want to cause a stir but DPMS has had had their issues with parts.
    I saw two triggers last year that looking down on the Top the Main Tigger Housing that holds the Disconnector Spring and Disconnector the Trigger Box was at least 25% off center from the Front of the Trigger to the Rear of the Trigger. What Receiver did you buy? But still suggesting you try another trigger or borrow one from someone that might have an extra Trigger and Hammer Group to try in your Receiver.
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  12. Bob T

    Bob T New Member

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    I was thinking about a drop-in, but wanted to discount anything outside the trigger group first. Thank you.
     
  13. JTJ

    JTJ Well-Known Member Supporter

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    Replacing the trigger cured the problem I was having. I saw the same thing happen to a guy at the range but he had a S&W M&P. Pull the trigger and a 2nd round would fire on the release. Scares you the 1st time it happens and then you worry if it is going to go full auto.
     
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  14. Bob T

    Bob T New Member

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    When I cycle the action by hand, it locks up every time. But, when it doesn't catch after firing a round, it does lock-up upon manually moving the carrier rearward just slightly. That's why I was thinking it was a timing mismatch. Could the buffer spring be a little too heavy?
     
  15. JTJ

    JTJ Well-Known Member Supporter

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    Optics Planet would not allow the 11% coupon the Rise trigger and is charging tax. I am happy with the JMT so I ordered another one at $89.99 shipped.
     
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  16. Bob T

    Bob T New Member

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    exactly!
     
  17. Sniper03

    Sniper03 Supporting Member Supporter

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    It is not the Buffer Spring! But be sure the Spring is all the way back on the Buffer where it belongs! I assume it is a standard CAR Collapsible Stock Spring. If it is mil-spec and the proper spring it should have no more than 37 Coils on the Spring.
    I might be mistaken but I think the Hammer and Trigger will solve the problem, unless the Receiver itself could be out of spec. which I doubt. Just for curiosity who's Receiver did you buy?
    03
     
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  18. Bob T

    Bob T New Member

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    Anderson Mfg.
     
  19. Sniper03

    Sniper03 Supporting Member Supporter

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    Normally they make a reasonable product. But anyone can have a fubar! But still beating on the DPMS Trigger and Hammer Group being the issue!
    03
     
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  20. armoredman

    armoredman Well-Known Member

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    My first build went binary on my first time to the range - bad disconnector. A $5 part and she was up and running. That was a Stag LPK.
    Replace the entire FCG if you can, but if you can't, take it to an expert and see if the disco is installed correctly, or is out of spec.
     
    Last edited: Dec 5, 2019 at 4:44 AM
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