Problem with new Build (AR15)

Discussion in 'Firearms' started by wallacem, Sep 20, 2018.

  1. wallacem

    wallacem Member

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    Got a Certac kit, built it with an Anderson lower. Fire it and it cycles fine, but trigger won't pull for second round. Open it and hammer is cocked, round in chamber. What gives? Wallace
     
  2. Wegahe

    Wegahe NRA Instructor

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    Not enough info...
    Did you check to see if it went back into battery before breaking it down?
    Did you check the lower function before attaching the upper?

    Place a piece of cardboard between the hammer and where it would hit the lower. Without the upper attached cock the hammer and pull the trigger letting the hammer strike the cardboard.. Repeat several times and see if the trigger resets.

    Then get back to us.
     

  3. wallacem

    wallacem Member

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    Yes it seems to go into battery just fine. I did check lower function. I did check hammer function many times, works great,,,,, until I shoot it. Then it will not shoot again, break it down, round is in chamber, in battery, hammer is cocked, and even broken down, cannot pull the trigger. I just came back from the range again from some testing. Found another clue. I moved the safety, to safe nd the hammer moved forward just a grunt. then moving the safety back to fire position and now can pull the trigger/
     
  4. Wegahe

    Wegahe NRA Instructor

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    Pull the hammer and check the fit of the pin.
     
  5. ber950

    ber950 Active Member

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    Try pushing forward on the trigger. Mine did that it was the disconnecter
     
  6. wallacem

    wallacem Member

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    Latest. It is that little notch on the back of the hammer catching the trigger and not allowing it to reset. If I just push the trigger forward it will jump off and allow the hammer to jump up a grunt, then it can be fired. I guess that is called the reset?
     
  7. Wegahe

    Wegahe NRA Instructor

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    Pushing forward on the trigger is resetting the trigger so it can be fired again. Still something is wrong because you should not have to manually reset the trigger.

    Disassemble the lower and reassemble it making sure everything is in properly. Pay close attention to the disconnector spring and the hammer spring. If either is misaligned or not installed properly this could be where the problem is.
     
  8. moe mensale

    moe mensale Well-Known Member

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    The disconnector spring has a big end and a small end. Correct installation is big end down, small end up.
     
  9. wallacem

    wallacem Member

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    hammer spg.jpg OK, took it over to my friends house that built it. Even though it seems to be working fine now, trigger resetting fine, he took it down just to check everything. He fouond the hammer spring was bent as shown in the attached photo. This is the second spring to come out of this lower bent just like this. Put a new one in and will try it. Any ideas why the
     
  10. Wegahe

    Wegahe NRA Instructor

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    Improper assembly. Double check your procedures when assembling the lower. I have seen this before with some first time builders.
     
  11. moe mensale

    moe mensale Well-Known Member

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    I'd say the hammer spring was put in backwards. The legs have to role out from the bottom of the coil and onto the top of the trigger pin. If the legs role out from the top of the coil the spring it's on backwards. Sorry for the non-technical verbiage.
     
    Last edited: Sep 24, 2018
  12. wallacem

    wallacem Member

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    Attaching a picture of the hammer spring installed. Not backwards. Only question this brings is why is one leg of the spring longer than the other? spring.jpg
     
  13. 175FO

    175FO Member

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    You've got the wrong hammer spring with that fire control group. Hammer springs that have one leg bent and a different length are for burst fire control groups.

    Do yourself a favor and buy a decent quality fire control group. The Laure MBT gets great reviews and is less than $100. Or go for a drop in unit like CMC.
     
  14. wallacem

    wallacem Member

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    I think you misunderstood me or I failed to explain properly. The legs on this spring are the same length, and they are perfectly parallel before installing. Installed, you can see that it sits as seen, and removing it, the short looking side will be bent upward.
     
  15. moe mensale

    moe mensale Well-Known Member

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    I don't think that's what he has. The burst fire hammer spring has 4 coils on the "normal" leg and 2 coils on the "bent" leg. And the 2 coils are larger. Look at the pic in post 9.
     
  16. moe mensale

    moe mensale Well-Known Member

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    This isn't a dig at you but that doesn't make any sense. If the legs are the same length and parallel before installation then they should be the same length and parallel after installation. I just looked at my ARs and all the hammer spring legs are the same length. The same length as the right side leg in your post 12 pic. That left side leg is too short. It's like it's getting wrapped around something during installation. Can you take a pic like in post 12 but with the hammer cocked?
     
  17. Groundhound

    Groundhound Active Member

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    You may find this video helpful if you haven't already seen it. It starts at Trigger & Hammer Assembly: (edit - forum software will not let me set the correct start point, it should start at the 9:11 mark)

     
    Last edited: Sep 24, 2018
  18. wallacem

    wallacem Member

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    here is picture with hammer cocked. Wallace hammer cocked.jpg
     
  19. Wegahe

    Wegahe NRA Instructor

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    OK...

    Pull the trigger and let the hammer fall against a piece of cardboard to protect the lower. DO NOT release the trigger then re-cock the hammer. It should lock in the cocked position even with the trigger pulled. Release the trigger and check to see if it resets.

    In the photo it also looks as if the hammer spring is twisted off center. Also (it may be the camera angle) it doesn't look as if the trigger spring is on both lugs of the trigger.
     
  20. Wegahe

    Wegahe NRA Instructor

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    Just noticed another issue...

    The right side of the hammer spring doesn't look as if it is in the right position on the hammer. It should run under like the left side. Instead it appears to run over the top of the retention of the hammer like it does on the left. This could account for some if not all of the length differences of the legs.