Feeding and lockback issue with new rifle w/pics... The diagnosis? - Page 3
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  1. #21
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    2 of the last 3 gastubes i've bought just flat out won't work, replaced them both and all is good. i use a punch thru the set screw hole that holds the gas tube in place while driving the roll piin in. examination of the barrel before replacing the tubes showed good alignment.
    There is a Clique, I ain't in it, Signed, Paranoid Deplorable

  2. #22
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    Quote Originally Posted by crayj View Post
    2 of the last 3 gastubes i've bought just flat out won't work, replaced them both and all is good. i use a punch thru the set screw hole that holds the gas tube in place while driving the roll piin in. examination of the barrel before replacing the tubes showed good alignment.
    Yes, most guys overlook that part of the build. They assume everything will line up perfectly when they really don't line up more than they do. Any restriction can slow the gases.
    AR Performance 6.8 SPC, 5.56 & Grendel barrels.


    Florida structural engineer & home design- Artibus Design
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  3. #23

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    Update:

    I took apart the low profile gas block and gas tube and it appeared the tube may have been off just slightly(you could see the OD of the gas tube in relation to the gas port). I re-positioned the gas tube to a more centered location over the gas port and took her to the range today with some of the same ammo I was shooting before and some Hornady.
    I put 1 round of the previously used Silver State Armory 110gr SP and it cycled perfectly. 2 more single shots with the same ammo(same box I was having consistent problems with) and no problems. The bolt locked back in the proper location each time. Put another 40 rounds of the 110 Hornady and likewise, no issue. She's working like a dream now. Looks like it was an undergassing issue caused by an out of alignment gas tube.

    Thanks for the help guys!
    Last edited by Gytheran; 03-26-2017 at 05:56 PM.

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  5. #24
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    did you use the roll pin to retain the tube in the block?
    There is a Clique, I ain't in it, Signed, Paranoid Deplorable

  6. #25
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    Quote Originally Posted by crayj View Post
    did you use the roll pin to retain the tube in the block?
    My question as well . I've built a lot if uppers and I've never seen anything that would suggest that the gas tube could be in any place other than where the pin puts it. Constructor's point is well taken, we can check to make sure things are lining up, but what's the remedy if they don't? Try a different tube or widen the hole?

    -Stooxie

  7. #26
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    Glad you figured it out. I'm still messing with mine, but not much time to check if it's fixed or not. Too much work these days.

    I might drill out the gas port a tad over and make an adjustable gas block out of what I have so it can be turned down if I drill too large...

  8. #27
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    Quote Originally Posted by stooxie View Post
    My question as well . I've built a lot if uppers and I've never seen anything that would suggest that the gas tube could be in any place other than where the pin puts it. Constructor's point is well taken, we can check to make sure things are lining up, but what's the remedy if they don't? Try a different tube or widen the hole?

    -Stooxie
    There has been instances where the gas tube ports have been slightly off, yes you can enlarge it slightly to match up with the gas block.

    To the OP, was your gas block off center with the gas port in the barrel?

  9. #28

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    Quote Originally Posted by semi_cop View Post
    There has been instances where the gas tube ports have been slightly off, yes you can enlarge it slightly to match up with the gas block.

    To the OP, was your gas block off center with the gas port in the barrel?
    Yes, it was. It was placement of the low profile gas block that I adjusted.


 

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