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MAK 90 will not fire in semi auto

Discussion in 'Maintenance & Gunsmithing' started by Mikey912, Jan 18, 2014.

  1. Mikey912

    Mikey912 Michigan New Member

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    I purchased a MAK 90 from a guy I worked with a while back and was told that it was never fired. After purchasing it, I had to install the trigger and oil it up before I took it out to test fire it. Upon firing it, I noticed that it would not fire in semi auto. When fired, it will reload the next bullet in the magazine but does not push the hammer back down. Would anybody be able to help me figure out why this is happening? I am not a gunsmith but I have a good knowledge of how things work and the only thing that I can think of that the vent holes in the gas tube are not allowing enough gas pressure through the tube to push the piston all the way back and knock the hammer back down. Any information would be greatly appreciated!
     
  2. saxon

    saxon springfield Active Member

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    taks some pictures of teh fire control group with out pictures it coud be dozens of things,,,,
     
  3. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    Yep take a pic looking down into the trigger group. Hammer could be in backwards...
     
  4. Mikey912

    Mikey912 Michigan New Member

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    Are these pictures any help? image.jpg

    image.jpg
     
  5. Mikey912

    Mikey912 Michigan New Member

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    image.jpg

    image.jpg
     
  6. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    Looks like its all installed correct. Take a look at the gas block, and see if you can spot allot of carbon where is seals around the barrel..

    Does it have the standard block or grenade launch block?
     
  7. Mikey912

    Mikey912 Michigan New Member

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    I don't see any carbon deposits around the gas block. It's a standard block on the rifle. I have only fired about 20 rounds out of it and cleaned it very well after each time it was fired. Do you think the vent holes on the gas tube could be letting too much pressure escape?
     
  8. Nwcid

    Nwcid Yakima and N of Spokane Well-Known Member

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    It is more likely something in the trigger group. How do you know the bolt is not going back?

    There is a possibility that the bolt is not being held back as it should in semi auto. It is possible someone tried to modify it and it did not work well. To test this cock the hammer with your finger. Keeping your finger on the hammer pull the trigger and slowly let the hammer up, never just let a hammer fly forward on its own. KEEPING the trigger held down the whole time re-cock the hammer again with your finger. It should stay back in a locked position. When you let your finger off the trigger the hammer should move forward slightly and stay hooked on the sear. Then you should be able to pull the trigger and repeat the whole process.
     
  9. SOrez

    SOrez SOR Active Member

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    I don't see a disconnector in your trigger.
     
  10. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    LOL oh yah, the disconnector and spring are missing, you can see the pocket where the spring is suppose to go!
     
  11. The Heretic

    The Heretic Oregon Well-Known Member

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    You say it does not push the hammer down?

    Do you mean that when the bolt goes back on firing that the hammer is not held down by the sear? Does the hammer follow the bolt back?

    Since you mention installing the trigger yourself, I would start there. I don't understand why you needed to install it since, but since you did that would be where I would start. Fortunately it should be easy to check.

    With no ammo in the rifle, and the rifle pointed in a safe direction - pull the trigger and while holding the trigger back, operate the bolt in the rifle with no ammo in the magazine.

    Do it forcefully - i.e., pull back on the charging handle smartly and then release it letting the bolt travel forward on its own. Once the bolt is all the way forward, release the trigger.

    Check each time that hammer has been retained by the sear by pulling the trigger. Does the hammer follow the bolt forward?

    If the hammer does follow the bolt forward, then you may have a problem with the retaining sear - the secondary sear; with how it is installed probably, since you mentioned you installed the trigger (why?).



    If that doesn't indicate a problem with the trigger group then:

    Does the bolt retract on firing and eject the cartridge?

    If manually operating the bolt all the way back results in the hammer being held down by the sear (I suspect this is the case), then it is possible that when you shoot the rifle the bolt is not traveling far enough rearward on firing to push the hammer down into the sear to be held by it.

    If that is the case (I am guessing it is), then you have to look at why the bolt is not traveling far enough back. Possible causes:

    a) The gas system. Not enough gas is pushing on the gas piston.

    This may be caused by weak ammo.

    This may be caused by a leaking gas piston.

    This may be caused by an improperly sized or aligned gas port.

    b) There is something preventing the bolt carrier from traveling all the way rearward.

    This might be caused by something being wrong with the magazine - maybe the bolt carrier is dragging on it and/or it is too far up into the receiver, or something like that. This is kind of unlikely though.

    There might be something else in the rails, or a buffer or something that is interfering with the bolt carrier travel.

    If you can manually operate the bolt and it seems smooth, then I would suspect the gas system or ammo.
     
  12. Mikey912

    Mikey912 Michigan New Member

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    I tried testing like you said and the hammer does follow the bolt forward while my finger is holding back the trigger. Yes it ejects the cartridge after firing. So I'm missing the disconnector and spring? Is there a specific kind that will fit the MAK 90 or will any AK disconnector work? Are they hard to install?
     
  13. SOrez

    SOrez SOR Active Member

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    AK parts are pretty much generic, so any AK disconnector should work if it has a standard AK hole in it . I would try to find a MAK 90 one though.
     
  14. Mikey912

    Mikey912 Michigan New Member

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    When I purchased the rifle, it did not have a trigger installed in it. It came with the trigger in the box, but I had to install it. Apparently it did not include the disconnector and spring like you talk about.
     
  15. Mikey912

    Mikey912 Michigan New Member

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    Thank you guys so much for all the help! I really appreciate you helping me locate my problem. I will order myself a disconnector and spring and then once it's installed I will post back with the results!
     
    Velzey and (deleted member) like this.
  16. The Heretic

    The Heretic Oregon Well-Known Member

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    Yeah, if the disconnector is missing then that would cause the hammer to follow the bolt forward.

    I sometimes mistakenly call it a secondary sear because it can be used as a fire on release sear with modification (not recommended - unsafe) and it acts just like the primary sear does.

    You can more easily verify the action of the disconnector without using the bolt:

    Make the rifle safe by unloading it.

    Remove the action cover.

    Remove the bolt carrier/spring/etc.

    Pull the trigger such that the hammer flies forward and keep the trigger pulled back.

    Push the hammer all the way back down into the sear area as far as it will go and then release it.

    If the disconnector is installed properly, the disconnector should prevent the hammer from going forward, the disconnector will hold the hammer long enough for the primary sear to engage it and at that point the trigger should be reset.

    If it is missing or not installed properly or there is something in the pivot point between the two sears, the hammer will not be retained.

    I should have suggested this from the beginning - sorry.
     
  17. saxon

    saxon springfield Active Member

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    yup as soon as i seen the pictures saw that too ;)