Gas Key Sealant

[prepare]

There seems to be no industry standard gas key sealant. The TM manual I have does not say either.
http://pdf.textfiles.com/manuals/MIL...4%20manual.pdf

[bamashooter]

Other than info stating to fire a few to let carbon act as a sealant, this is the only one I've ever seen to reference Permatex.

[prepare]

Thanks!

[bamashooter]

You bet.

[hotrodder636]

SOTAR has a couple of YT videos that talk about it. I think he uses some sort of shellack.

Check out his video here:
https://youtu.be/GCFAtcV1c8k

[rjacobs]

as with other things in life... I go in dry...

[rjacobs]

LMT uses something from Loctite, I believe it's gasket sealant 518. I have a little bottle of it for gas keys, but I prefer to use nothing.

Not on the lmt carrier I changed a key on a few weeks ago...that had screws that were not torqued before staking... Guess whoever assembled it also didn't put sealant on it.

[556Cliff]

Not on the lmt carrier I changed a key on a few weeks ago...that had screws that were not torqued before staking... Guess whoever assembled it also didn't put sealant on it.

Wow, you wouldn't expect that from LMT... I recall getting one LMT enhanced carrier without the sealant (might have been my last a few years ago), but they were all torqued to spec and were probably the most difficult gas key screws I've ever had to break loose.

[rjacobs]

Wow, you wouldn't expect that from LMT... I recall getting one LMT enhanced carrier without the sealant (might have been my last a few years ago), but they were all torqued to spec and were probably the most difficult gas key screws I've ever had to break loose.

yea thats why I buy LMT stuff. This was from circa 2013 or so I guess. Gun ran fine suppressed, but un-suppressed it was erratic. I originally placed blame on running an H2 buffer(shared lower with 9" 300blk upper) and it being a 10.5", then I found the gas key was loose. I had emailed LMT a few times back in 2014 or so when I first realized the key was loose to attempt to warranty it. Never got a response to fix it under warranty and it wasnt a huge deal to me. Life changed and I wasnt able to shoot near as much so a lot of stuff moved the back burner. Recently built another SBR lower so this upper was going back into the rotation so I needed to change the gas key. Staking broke free easily enough(it LOOKED good) and I saw no evidence the screws had actually moved in the staking. Went back on with a BCM gas key and some OCKS screws. Gun functions 100% now.

Long story short, at least in 2012-2013 time frame LMT did NOT use any kind of sealant under the gas key. Standard M16 carrier.

[prepare]

The take-away for me is; we have the formula for doing the job right. If you're doing a field repair and don't have the right sealant, I get it. But if I'm at my bench I'm going to stick to the proper standard.

Lap the key, ensure both surfaces are clean, apply the Permatex, the OCKS screws, and 58 in lbs of torque. Then stake the carrier key using a MOACKS.

Note; Lightly dipping a straw into the Permatex container and then carefully placing the straw over the gas port hole of the carrier makes a neat circle around the the gas port hole.

After that I run a pipe cleaner through the gas key to remove any excess that may have gotten into the gas pathway.