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Posted: 10/1/2011 7:44:29 AM EST
I have a 18'' rifle with rifle length gas tube. It functions 100% with M855 and M193, locking the bolt back evrytime. With any 75 gr, (PPU, Hornady, FGM, Black Hills) it functions 100% it just will not lock the bolt back, ever. Any idea's?
I have also tried Magpuls, as well as USGI with the green followers. It just won't lock back with anything other than NATO spec....
Link Posted: 10/1/2011 2:08:42 PM EST
What buffer are you running? That would be the first place I would look. Willing to bet you have a heavy or extra heavy buffer which you don't need in a rifle length gas sysem. All you need is a standard weight buffer.
Link Posted: 10/1/2011 2:42:51 PM EST
hmm, good place to start looking. Thanks...
Link Posted: 10/3/2011 6:32:48 AM EST

Mine is an 18" with rifle as well, and I had to drill the gas port out to approxiamtely .100" because of the dwell time issues. Rifle ran 100% suppressed, but not unsuppressed, so it was an under gassed situation. Do a search on this site for proper gas port dimensions.

It sounds as though yours might be that as well. However advice to check carrier weight, and buffer weight and buffer spring is better than to start with opening of the gas port. I would also check the alignment of the gasblock to the gas port to be sure you are getting 100% of the gas impulse.

Good luck
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