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AR15.COM
10/19/2012 10:45:27 AM EDT
I sent an email to bcm but didnt really get much of an answer so im hoping someone here might be able to help.


Email i sent to BCM:

How tight should the gas block fit on the barrel before set screws are tightened? I installed mine, its not lose enough to rattle, but it is easily rotated with almost no resistance before tightening the set screws, so i worry it could be leaking gas. This is on a standard M4 style BCM upper, government profile barrel, carbine gas system.  I test fired the rifle and got a couple failures to feed through one mag so i am trying to figure out what could cause that. It ran flawless before. Thanks.


Im 99% sure it is aligned properly so im not sure what else it could be, i figured i would be saving myself some trouble buying a BCM gas block for my barrel but apparently something isnt quite right.
10/20/2012 5:55:40 PM EDT
[#1]
Gas blocks with set screws have to have some dimples drilled into the barrel so it wont spin. Rainier Arms sell a jig so you can do it yourself. Any smith will be able to do it also.
10/20/2012 6:52:01 PM EDT
[#2]
I dimpled the front set screw following BCM's instruction