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Thread: help me diagnose an issue

  1. #1
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    help me diagnose an issue

    couple months back I took my AR out for the first time after installing a new low pro gas block and midwest industries T12. I did not do the installation of either.

    While at the range i was running into failure to ejects and failure to loads. Initially I thought it might be a gas issue. After not being able to run 20 rounds consecutively i gave up and went home. Once home i went to remove the rail only to find the set screw completely stripped. At this point i was madder than hell and said screw it and put it in the safe.

    fast forward a few months and i've finally got up the motivation to f with it again. Got a set of screw extractors and it pulled it right out. So i unscrew the rail and here comes more issues. Two of the gas tube holes in the barrel nut the rail screws onto are now one, and there are pieces of metal floating around in the others.

    Biggest issue. Something looks off. i could see that the gas block is canted to the left. so i shoulder the now de-railed weapon and sure nuff it is, and it looks like the tube may be kinked a bit.

    is this normal? isn't the gas block/tube supposed to be center line over the axis of the bore?

  2. #2
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    yes, the port is supposed to be on the centerline (perfectly vertical) with respect to the gas tube hole in the receiver, and barrel extension pin. if your gas block is canted, check the port. if the port is also canted, then chances are your barrel extension pin or receiver notch is messed up. someone might also have tightened the barrel nut, saw that it didn't line up with the gas tube hole, and do a bit of filing to insert the gas tube instead of going up or down a hole.
    anyways, pics of everything would help. or, ask the person who put it together.

  3. #3
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    Quote Originally Posted by militarymoron View Post
    yes, the port is supposed to be on the centerline (perfectly vertical) with respect to the gas tube hole in the receiver, and barrel extension pin. if your gas block is canted, check the port. if the port is also canted, then chances are your barrel extension pin or receiver notch is messed up. someone might also have tightened the barrel nut, saw that it didn't line up with the gas tube hole, and do a bit of filing to insert the gas tube instead of going up or down a hole.
    anyways, pics of everything would help. or, ask the person who put it together.
    for whatever reason he's dropped off the face of the planet. i actually think you might know him. or at least of him. we have a couple of mutual friends believe it or not.

    pics coming in a few. gotta break out the camera

  4. #4
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    Is this a buddy or a gunsmith?

    No way I would wait a couple of months before I went back to "f with it" if I had paid to have a rail and gas block installed.

    If the gas block is canted it could be partially obstructing the gas port causing the rifle to short stroke and giving you the problems.

    If the whole barrel is canted and the block is actually over the port, then it should probably still run, but would still be a hack job.

    Pictures would be helpful to further diagnose.

  5. #5
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    in this first picture you'll note what i was talking about with the two gas holes becoming one. also in this picture note the two holes next to the gas tube? see how they are flared out?

    another shot of the flared out holes


    here's some of the alignment. it didn't really come out like i'm seeing it




    also if you'll scroll back up three pictures i think you'll see what can only be described as a gap between the gas block and the tube. it's causing build up on the tube. this may be normal, i don't know. i'm an ak guy.

  6. #6
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    That barrel nut or whatever it is looks like it was chewed up during the installation process. This is one of the downfalls of those types of nuts.

    It would also appear that the barrel nut is nut correct either and that the gas tube is slightly bent due to the pressure being put on it.

    As for the rest, you are screwed. You waited too long to address the issue and you need to find someone competent to fix this.



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  7. #7
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    The YHM bbl nuts need to be installed with either a YHM 3pin or PRI 5 pin wrench using a USGI style 3 pin bbl wrench usually results in broken/chipped bbl nuts like that. And yes your gas block isn't centered/aligned correctly. I'm 99% certain your failures are gas related and would be remedied by aligning the gas block.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  8. #8
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    what i was hoping was that i could loose the three set screws on the bottom of the block, pulling the block/tube, replacing the tube and installing the new vtac rail i got coming.

    is it that simple or does a smith need to take a look at it?

  9. #9
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    Quote Originally Posted by calicojack View Post
    what i was hoping was that i could loose the three set screws on the bottom of the block, pulling the block/tube, replacing the tube and installing the new vtac rail i got coming.

    is it that simple or does a smith need to take a look at it?
    You need at least a very experienced armorer or gunsmith, although some of those are truly clueless too.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  10. #10
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    Quote Originally Posted by Robb Jensen View Post
    You need at least a very experienced armorer or gunsmith, although some of those are truly clueless too.
    that's the problem i ran into with the first installer. i won't go into details other to say that it went to a military installation and to their armorer for "help" with the installation.

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