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12/26/2011 7:18:45 PM EDT
I received a barrel with the gas hole only partially drilled, yes, it appeared normal, but was not all the way through.  Needless to say this did not work.  So I drilled it with a 1/16 " drill and function is now 90%+.  My question is what is the correct size for this hole, is it possible I drilled the hole slightly undersized and am getting only marginal gas?

This was a present for my son and when we did the build Christmas he was more than a little disappointed he had a  pull bolt action.  We trouble shot it and found the partial hole while checking to see it there was a burr or debris blocking it.
12/26/2011 7:47:52 PM EDT
[#1]
Need to know the barrel overall length as well as the gas system length and gas block diameter in order to give you better information.  Or you can determine experimentally what works for you by just sequentially increasing the port size until you get up to the level of energy you want in the system.
12/26/2011 8:50:44 PM EDT
[#2]
gas port sizes normaly range from .063 to .092 in size. start at the small end of the spectrum and see whats the smallest hole that works reliable then stop.
12/30/2011 3:14:25 PM EDT
[#3]
Thank you for the advice.  It seems to be running 100% now that I have put about 60 rounds through it.  Had it out today and ;rn about 10 rounds each of PMC, Wolf and 55 gr hand loads, all functioned fine and were accurate to boot.  Now if it gets spotty when dirty I will know to increase the hole size slightly.
1/2/2012 11:11:38 AM EDT
[#4]
On a new build it is common for there to be some leakage from the FSB or gas block until there is a slight carbon buildup from firing.  I have build a couple of guns that did spit a bit of gas for the first mag or so.  Your problem may already be solved.
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