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Blown gas rings on M4s

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We've been out training for 2 weeks we're on our third week. We've noticed that some of our m4s have been having issues. Cleaning our M4s we noticed that gas rings are missing from the bolts of the M4s that are having issues. These are brand new M4A1s made by FN. We had beat up Colt M4s before that never had this problem. We're scratching our heads as to whats happening. We did some shooting but it was nothing serious.
 

EPS

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What kind of BCG are in them.
My sisters gun burned up her gas rings .
I bought a fail zero BCG .
And have had no problems.
But it could be over gassed.
I'm not a gun Smith but usually it happens to over gassed guns
 

v0lcom13sn0w

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ive had gas rings get worn out after 5-6k rounds. they were still on the bolt but they were paper thin and more of a “C” than an “O” gun still worked but i had it apart and i replaced them. i was told, a general rule of thumb is if you can extend the bolt out in the carrier and stand the BCG upright on the bolt face, it shouldnt collapse if your rings are good.

i always carry extra rings in my stocks.
 

EPS

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ive had gas rings get worn out after 5-6k rounds. they were still on the bolt but they were paper thin and more of a “C” than an “O” gun still worked but i had it apart and i replaced them. i was told, a general rule of thumb is if you can extend the bolt out in the carrier and stand the BCG upright on the bolt face, it shouldnt collapse if your rings are good.

i always carry extra rings in my stocks.
That's what you do
If the bolt slides in from just the weight of the carrier then the rings are bad.
 

DirectDrive

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We've been out training for 2 weeks we're on our third week. We've noticed that some of our m4s have been having issues. Cleaning our M4s we noticed that gas rings are missing from the bolts of the M4s that are having issues. These are brand new M4A1s made by FN. We had beat up Colt M4s before that never had this problem. We're scratching our heads as to whats happening. We did some shooting but it was nothing serious.
Looks like this is 100% on FN to fix this.
As in send you some new BCG's (it could be a carrier issue chewing them up)
 
OP
R
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Again these are brand new M4A1s. We noticed the issues during live fire some M4s became bolt action M4s. Some guys said their gas rings fell out when they took their bolts out of the carrier. Others just said they were missing. i stood my BCG up on the bolt and the carrier collapsed down to the bolt and would not stay up. So im guessing my gas rings are also toasted. So far I've fired 12rds to zero and 40rds to qual. Then i fired 5 30rds mags on auto to burn up range ammo. Again ive never encountered this problem with beat up colt M4s and M16A2 or even the FN M16A4.
 

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