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Uzi firing pin

Discussion in 'Gunsmithing and Repairs' started by 7.62 Nato, Dec 20, 2012.

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  1. 7.62 Nato

    7.62 Nato Member

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    I am checking out an (unfired) Uzi carbine (model B)that will not fire. The firing pin strikes the primer but does not set it off. Have tried diff, brands of ammo. All parts are new as came from manufacturer. I've checked for burrs, obstructions, and damage. Everything appears to be correct. The firing pin will protrude from the bolt face by .030-.032" when held forward manually with the firing pin safety held out of the way.

    I wanted to compare this firing pin with a new/ known good pin but haven't found any available. Someone suggested a headspace problem but there doesn't appear to be a problem there. The cartridge is contacting the bolt face and is also held by the extractor.
     
  2. Jim K

    Jim K Member

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    I can't fully dianose the problem long distance, but generally, .030 is about half normal firing pin protrusion. Headspace is not usually a problem with a blowback action, which the UZI is.

    Jim
     
  3. 7.62 Nato

    7.62 Nato Member

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    Yeah, someone threw out a .050" figure but it sounded like a guess. I like to see specs, or compare with a known good part when it's not something I deal with on a daily basis.
     
  4. NCsmitty

    NCsmitty Member

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    I recommend checking out www.uzitalk.com, as they have a wealth of info on minis and standard versions. Mentioned was the protrusion on the model "B", it should have a protrusion half the diameter of the firing pin.
    I'm only passing along what I read, as I have no experience with Uzis.


    NCsmitty
     
  5. 7.62 Nato

    7.62 Nato Member

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    I get a malware warning when I try to go on the Uzi forum.
     
  6. Jim K

    Jim K Member

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    I don't know what it should be, but mine measures .058".

    Jim
     
  7. 7.62 Nato

    7.62 Nato Member

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    Thanks, Jim.
    That's in line with what I suspected. Now I need to find out if the pin is short, or the bolt is machined out of spec. I'm hoping it's the pin.
     
  8. BBBBill

    BBBBill Member

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    .050-.060" is pretty common for firing pin protrusion. Pretty hard to stretch a firing pin. Those bolts are harder than woospecker lips. ;)
     
  9. 7.62 Nato

    7.62 Nato Member

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    I removed the firing pin and measured the length to the front shoulder. It is 2.155". The firing pin channel in the bolt from back to face measures 2.125" giving me a difference of .030".
     
  10. BBBBill

    BBBBill Member

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    Is it an IMI manufactured gun or a clone? Checking UZI TALK, I found several posts indicating that .042" will work. I would not go over .055". I got no malware warnings.
     
  11. 7.62 Nato

    7.62 Nato Member

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    It is an IMI receiver imported by NHM Sacramento, CA, assembled by Vector Arms. The gun is unfired.

    The headspace seems to be on the short side if anything. The cartridge sticks out of the chamber by .220". I found that when I was loosening the barrel nut with the dummy cartridge in the chamber the bolt moved forward by .060". Pushing the barrel back in and tightening the barrel nut caused the bolt to go back by .060" again. The cartridge rim was under the extractor. Measurement from the back of the barrel to the back of the barrel stop shoulder is approx. 7 7/16".

    I'm running Malwarebytes and I only get the warning when I try to go into the talk forum. The only other time I ever got that warning I got a virus. That was not fun to get rid of.
     
  12. BBBBill

    BBBBill Member

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    I'm far away from mine, so not able to help with any measurements. I thought Vector only built on the Group Industries receivers. I have heard of some issues with their late production stuff, but no first hand knowledge. I did have an aftermarket barrel one time that had the locating collar machined incorrectly. It was off by about .040", stopping the barrel just a little bit forward of the correct spot. Couldn't see it without having another barrel right next to it. Gun would not fire with that barrel in place.
     
  13. 7.62 Nato

    7.62 Nato Member

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    When I researched this gun I couldn't find any info on Vector building on anything but Group One receivers. I looked up the parts and stampings seperately. All are correct, I just can't find any info with them all on the same gun. The receiver has IMI, NHM, and Vector stamps.

    When I found out the gun won't fire it got more intriguing. He just put it in his safe and it's sat there for a few years. I'm checking it out to keep mind and hands busy while I'm off on medical. Uzi parts, and facts seem to be scarce around here. I did speak with one person that seems to be knowledgable. He would try to squeeze me into his busy schedule but I suggested we wait until after the holidays.
     
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