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Thread: New build double fires then no hammer reset

  1. #11
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    Also google David Olufson

  2. #12
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    jafount,

    Please read this before you make your next post. https://www.m4carbine.net/showthread.php?t=63137

    That way we don't get to page 5 to find out something we should have known on page 1.

    All buffers that I have, have little weights in them and they rattle when you shake it. That's normal.

    Are you saying that the weapon will fire approx. 2 rounds, chamber another and then not fire? Can I assume that the hammer is in the forward position on that last round? If so, I have a very good feeling that you have an issue of "bolt bounce'.

    We just had another similar case on this board and I suspect that is your problem.

    A word of caution. You need to be careful where you go when you are conducting your test fires. A weapon that malfunctions like yours can land you in hot water if the wrong people are around.



    Quote Originally Posted by jafount View Post
    Hi all. I recently built an AR for a friend. I've built six different rifles with no issues though in my own builds I'm very aware of the "buy cheap buy twice" mantra.

    My buddy spent a lot of money on some parts, then underspent on others. Specifically, he bought a kit that included buffer tube, spring, buffer, stock.

    The weights inside the buffer slide when you tip it. I suspect this may be causing some sort of bump fire situation. It shoots two rounds, cycles and goes into full battery, but doesn't reset the hammer. Any ideas? I haven't thrown a good buffer in there yet but any other input would be great.



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  3. #13
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    Is this a full auto gun??? Bolt bounce is an issue in full autos.

  4. #14
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    Quote Originally Posted by az doug View Post
    Is this a full auto gun??? Bolt bounce is an issue in full autos.
    If the hammer is dropping on a live round and not firing, bolt bounce could be a factor. There may be other reasons why that hammer is dropping in the first place, but not firing the round might be because the bolt carrier has bounced out of battery.

    I've had out of spec lower parts that would fire upon trigger let off. I'd suggest the OP shoot this weapon with a good trigger follow through to make sure the hammer isn't dropping on let off.

  5. #15
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    Quote Originally Posted by CCK View Post
    Also google David Olufson
    My thoughts exactly

  6. #16
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    Quote Originally Posted by markm View Post
    If the hammer is dropping on a live round and not firing, bolt bounce could be a factor. There may be other reasons why that hammer is dropping in the first place, but not firing the round might be because the bolt carrier has bounced out of battery.
    I agree that bolt bounce could be a factor as to why it is not detonating the primer.

    Often times in a semi-auto the cause is the hammer following the bolt carrier home. As the bolt carrier moves forward the hammer is pushing on the bottom of the carrier. When the gun goes into battery the hammer does not have enough energy to strike the firing pin and detonate the primer.

    "Bolt bounce" occurs when the auto sear is tripped thereby releasing the hammer. The bolt goes into battery and bounces just slightly out of battery just as the hammer strikes the firing pin. Normally this timing is not an issue in a semi.

    In the OP's case the hammer should not be releasing, so the question why does it? Disconnector hook angle, the hammer hook where the disconnector engages, timing of the hammer's release from the disconnector, weak springs, out of spec parts...?

    In this case it is a good thing that it stops on a live round in the chamber.

  7. #17
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    Let's set the record straight. Olufson was an idiot who KNOWINGLY installed a full auto fire control system in his weapon and then after he knew it was firing more than one round for every pull of the trigger HE LET AN 18 YEAR OLD take it to the range and shoot it.

    It has nothing to do with a weapon that "accidentally" was firing in full auto.

    Quote Originally Posted by ac guy View Post
    My thoughts exactly



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  8. #18
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    Copied from a Military TM

    9. FAILURE TO COCK.

    Step 1. Inspect for worn or broken trigger nose or trigger spring.

    Step 2. Inspect for worn or broken hammer trigger notch.

    Step 3. Inspect for worn or broken hammer disconnector hook.

    Step 4. (Full Auto Only) Inspect for worn or broken automatic sear hook. (Full Auto Only)

    Step 5. Inspect for worn or broken disconnector hooks.

    Step 6. Inspect for weak, broken, or missing disconnector springs.

    There are more steps. All but one pertain to full auto guns only. The other step that pertains to a semi would be short stroking. Since the OP's gun is cycling far enough to pick up a live round from the magazine I believe the carrier is traveling far enough cock the hammer. (I have been known to be wrong.)

  9. #19
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    Quote Originally Posted by Iraqgunz View Post
    Let's set the record straight. Olufson was an idiot who KNOWINGLY installed a full auto fire control system in his weapon and then after he knew it was firing more than one round for every pull of the trigger HE LET AN 18 YEAR OLD take it to the range and shoot it.

    It has nothing to do with a weapon that "accidentally" was firing in full auto.
    Thank you. I did not want to get into that debate here, but you are 100% correct.

  10. #20
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    Let's set the record straight. Olufson was an idiot who KNOWINGLY installed a full auto fire control system in his weapon and then after he knew it was firing more than one round for every pull of the trigger HE LET AN 18 YEAR OLD take it to the range and shoot it.

    It has nothing to do with a weapon that "accidentally" was firing in full auto.
    Read the wikipedia article on it...pretty slanted. I think if my selector had three positions, that would be a...clue. Kind of just glanced over that.

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