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Should I just drill the gas port?


Cmudogtag
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I scoured this forum for all the best advice on correct parts for a reliable 308 AR.  I was hoping my first post would be a thank you for helping with my success.  Nope! It won’t cycle.
 

I am pretty sure the gas port is too small and the rifle is under gassed. Before I drill out the gas port I am requesting a review of my build for any errors.  
I slowly went trough 20 rounds of Federal Match 175 (expensive 😖).  Rounds barely dribble out and I had a few stove pipes. The gas block is seated correctly and I can’t detect any issues with alignment. 

  1. Aero M5 upper/lower + M5 LPK
  2. Wilson Combat Super Sniper .308, 18”, .875 GB seat, .090 gas port, rifle length
  3. Wilson Combat BCG
  4. Wilson Combat AR10 rifle length gas tube 15.5” - reaches more than halfway through cutout 
  5. SLR Rifle Works AGB - wide open
  6. Magpul UBR gen 2 stock
  7. Armalite AR10 EA1095 spring
  8. Armalite H3 Buffer

 

 

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1 hour ago, Cmudogtag said:

I scoured this forum for all the best advice on correct parts for a reliable 308 AR.  I was hoping my first post would be a thank you for helping with my success.  Nope! It won’t cycle.
 

I am pretty sure the gas port is too small and the rifle is under gassed. Before I drill out the gas port I am requesting a review of my build for any errors.  
I slowly went trough 20 rounds of Federal Match 175 (expensive 😖).  Rounds barely dribble out and I had a few stove pipes. The gas block is seated correctly and I can’t detect any issues with alignment. 

  1. Aero M5 upper/lower + M5 LPK
  2. Wilson Combat Super Sniper .308, 18”, .875 GB seat, .090 gas port, rifle length
  3. Wilson Combat BCG
  4. Wilson Combat AR10 rifle length gas tube 15.5” - reaches more than halfway through cutout 
  5. SLR Rifle Works AGB - wide open
  6. Magpul UBR gen 2 stock
  7. Armalite AR10 EA1095 spring
  8. Armalite H3 Buffer

 

 

Have you measured your gas port diameter with a digital caliper?  If it is between .090 and .095 (based on what @98Z5V stated for my build, which is quite similar), then you're okay.  IF NOT, then drill baby drill!  (FWIW: My gas port diameter, measured with digital caliper, was .0835 from factory; rifle would not cycle normally.  After much adoo, I drilled it out to .0945 and the rifle runs flawlessly!!!)

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Your gas port diameter is close, but all barrels are different.  You should be good for a journal diameter of 0.875".  Based on what you're saying your firing conditions are, drill it.  Hit 0.093" and see what happens.  Makes sure that the adj gas block is wide open, like you stated - verify that first.  But, since you have adjustable gas, drill that fucker.  0.093" is first, check function.  After that, if it's not solved, we go 0.096", and that will certainly fix it.  You have zero penalty for going big right off the bat, to 96, based the the adj block.  Punch it up.

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51 minutes ago, 98Z5V said:

Your gas port diameter is close, but all barrels are different.  You should be good for a journal diameter of 0.875".  Based on what you're saying your firing conditions are, drill it.  Hit 0.093" and see what happens.  Makes sure that the adj gas block is wide open, like you stated - verify that first.  But, since you have adjustable gas, drill that fucker.  0.093" is first, check function.  After that, if it's not solved, we go 0.096", and that will certainly fix it.  You have zero penalty for going big right off the bat, to 96, based the the adj block.  Punch it up.

Thanks for the affirmation. I am just going to take it up to .096 and be done. I enjoy the build aspect but i wold rather shoot than keep fiddling with it.  

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I drilled the gas port out to .096 and now the rifle just runs. The gas block is adjusted about midway through it’s range.  I put 200 rounds down the barrel without a single issue.  I think it’s broken in and ready to go.  

Thank you all for the assist and all of the knowledge I acquired on this forum. My original plan definitely would have failed had I not done my homework.  

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13 minutes ago, Cmudogtag said:

I drilled the gas port out to .096 and now the rifle just runs. The gas block is adjusted about midway through it’s range.  I put 200 rounds down the barrel without a single issue.  I think it’s broken in and ready to go.  

Thank you all for the assist and all of the knowledge I acquired on this forum. My original plan definitely would have failed had I not done my homework.  

It's always great to end up with a well running rifle.

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3 hours ago, Cmudogtag said:

I drilled the gas port out to .096 and now the rifle just runs. The gas block is adjusted about midway through it’s range.  I put 200 rounds down the barrel without a single issue.  I think it’s broken in and ready to go.  

Thank you all for the assist and all of the knowledge I acquired on this forum. My original plan definitely would have failed had I not done my homework.  

Good job, man - I love to see gas guns fixed and running right.  Very well done.  :thumbup:

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