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Posted: 7/8/2009 6:23:53 PM EDT
| It appears that gas is seeping out of the base of the gas key on one side in my 14.5" CMMG M4 upper. Is there a fix for this besides just buying a new complete bolt carrier? |
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Pics? Might be worrying about nothing if the rifle is functioning.
Had a Bushmaster with a loose gas key show no signs of leaking from the base, but would stop cycling at random. Tried wiggling the gas key but it didn't move... checked the hex bolts as an afterthought - they turned freely with light finger pressure. Retightened and staked. No more problems. |
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Pull the allen screws and pitch them in the trash.
Now using lapping compound, hand lap the key into the top of the carrier mating surface. Once that is done, reinstall new allen bolts to 37 in lbs, followed by re-staking the sides of key materal into the side spines of the keys. If you don't want to lap, then there is always using loctite between the two surfaces to make a seal, if the leak is not bad enough that you need to lap the parts. Note: after lapping the parts, make sure to check the carrier key to gas tube alignment (carrier alone with out the bolt in the upper, and tweak the gas tube above the barrel to get it back into check). |
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The bolts are torqued to 37 in lbs, and best not to try to reuse them since they may not hold the needed torque a second time.
Could be that the bolts where over torqued and the reason that the bolt is leaking, and now in a semi stress fractured/ every stretched stake, and just waiting to snap. Granted that you could alway try to reuse them, but after you have a few snap on you from the above problem, and have to take the time to dig the broken seconds out of the carrier, it's just not worth the hassle of trying to use them a second time. |
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