MP5 failures to fire issue.
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Thread: MP5 failures to fire issue.

  1. #1
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    Default MP5 failures to fire issue.


    Hi folks, I've owned NFA MP5's since the 80's and have always managed to troubleshoot problems with my guns, but not this one. I have a IGF MP5 made from when he was doing fantastic work, it was made with a Turkish flat and all German parts that I first bought as a SBR and it now wears a post sample pack. The gun has always run just fine, likes genuine HK mags, is clean and properly headspaced. Has fairly new a HK newest generation extractor and extractor spring since winter... no problems with extraction before or after.
    So now the gun will shoot two to four rounds and then not have the hammer cocked. I have tried several mags and several brands of 115 and 124 FMJ round nose. The next round always feeds just fine (I clean the chamber often with a HK fluted chamber brush and gently bronze brush the face of the chamber), but the hammer is not cocked and the round of course won't fire. If I pull back on the bolt just enough to confirm a round in the chamber and let it slam home it's enough to cock the hammer and fire. Semi or full does not make any difference. Firing pin looks good, the spring is new this year just because I bought a bunch of HK ones.
    I have extra recoil springs but haven't tried that as I have some new rivets on order but I'm doubtful it's a recoil spring problem... or could it be?
    Confused in Alaska

    George from Alaska

    HK45T DA/SA, HK45T Light LEM, Mark 23 90's era, no lockout, P30L v3, P30L Light LEM, USP .45 Elite
    rrMP5 SEF select fire - Flemming from a 94
    IGF MP5 SBR - now a post sample
    IGF HK33 pistol - now a post sample
    RDTS MP5 pistol from a German HK parts kit - now a post sample
    RDTS MP5 SD pistol from a German HK parts kit - now a post sample
    TSC MP5K N pistol from a German SP89 - now a post sample
    bunch of suppressors
    other NFA machine guns
    07/02

  2. #2
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    I'm not a gunsmith but, I would check the hammer and sear engagement area for excessive wear or damage. How many rounds have you put through this piece?

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    sounds like the hammer is following the bolt forward. Time to service the trigger pack?

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  5. #4
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    Hammer, sear and all other parts in the trigger pack look good... all German and the parts look and function like the parts in my other seven or so trigger packs. Probably 5,500 rounds through this gun, some suppressed. My original rr German MP5 went 105,000 rounds since 1985 before the hammer broke about three years ago. I kept all my 1,000 count primer box end tabs and end cutouts from 1,000 round cases of 9mm to keep track.

    Quote Originally Posted by Jeffe View Post
    I'm not a gunsmith but, I would check the hammer and sear engagement area for excessive wear or damage. How many rounds have you put through this piece?

  6. #5
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    That's exactly what it sounds like to me too, although I can't seem to find why. I have other packs so I am going to swap it out this morning and do a complete tear down of the problematic one. Thanks!

    Quote Originally Posted by Mike748 View Post
    sounds like the hammer is following the bolt forward. Time to service the trigger pack?

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    Wonder if there is up and down play in the trigger housing in the front where it is clipped and pinned just enough for the trip lever not to engage correctly when the bolt is all the way shut making the gun not fire. A bit of upward pressure on the grip frame may help trip the lever allowing the gun to actually fire. It could be the smallest amount of play for that trip lever to engage.
    Spent most of my tax return on Hk parts, booze and ammo....the rest I just wasted

  8. #7
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    It's always been a perfect feeling fit since I got it from the original owner on this site. I'll be taking that whole housing and pack out later today but before I do I definitely will check out what you suggested as I have had that happen before. Thanks!

    Quote Originally Posted by Anopstyx View Post
    Wonder if there is up and down play in the trigger housing in the front where it is clipped and pinned just enough for the trip lever not to engage correctly when the bolt is all the way shut making the gun not fire. A bit of upward pressure on the grip frame may help trip the lever allowing the gun to actually fire. It could be the smallest amount of play for that trip lever to engage.

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