View Full Version : Gas Key Sealant
There seems to be no industry standard gas key sealant. The TM manual I have does not say either.
http://pdf.textfiles.com/manuals/MILITARY/Army%20M16A2%20and%20M4%20manual.pdf
bamashooter
04-18-21, 07:13
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.
https://i.imgur.com/HajDBEV.jpg
bamashooter
04-19-21, 06:52
You bet.
hotrodder636
04-19-21, 06:55
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
as with other things in life... I go in dry...
I believe you would be more likely to create a problem than solve one using a sealant. A thin shellac would be better than a thicker gasket sealant though.
Since using nothing works, I'll stick with that.
ETA: I don't have my notes with me from Will's class. I'm in Prescott, AZ this week. I seem to recall him saying machine tolerance should be enough. I can update when I get home. Assuming I remember, before I head to Denver Monday night. Attending his armorers class (which I considered very good instruction) is as close as I come to being an honest mechanic. I generally go with the title "shadetree gun butcher" just to keep myself honest.
I've sealed and not sealed and never had a problem either way. If I was to build a BC today, I would not use sealant.
I haven't done a key install in years. But I lap the surface and was using some rockset on a few. I think someone said rockset was not a good idea, but I never had any leakage issues.
I reached out to BCM, Sionics, Toolcraft, and Aim Surplus. They all report using Permatex Aviation Form A Gasket.
I then contacted Permatex. Permatex Aviation Form A Gasket 80017 and 80019 are the same product. 80017 is 16oz. and 80019 is 4oz. The 3D was an old numbering system that is no longer used.
I reached out to BCM, Sionics, Toolcraft, and Aim Surplus. They all report using Permatex Aviation Form A Gasket.
I then contacted Permatex. Permatex Aviation Form A Gasket 80017 and 80019 are the same product. 80017 is 16oz. and 80019 is 4oz. The 3D was an old numbering system that is no longer used.
Contacting manufacturers for accurate information goes against the whole point of the internet. :p
Sometimes the manufacturers wont give you the information you want. In this case they did.
Apparently Permatex Aviation is the industry standard.
I was being a smart aleck.
IE: "The internet is for misinformation and lies, not actual facts" ;)
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.
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.
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.
518 is what I use. I bought it last time I did some research on it. I doubt using it or not matters, but OCD. One tube will probably last a lifetime for me. I generally avoid effing with gas keys.
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.
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.
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.
But did you follow the assemble drawing and stake the opposing sides of the screw simultaneously? Or did you run the screw in on one side at a time putting a side force against the unsupported screw head? Just mentioning it since most videos I have seen do it one screw at a time.
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.
As I stated elsewhere, when the screws are tightened to the proper torque the screws are nearly at the yield limit for the screws. If the screw yields (stretches) the torque will disappear.
The absence of torque on removal is not positive proof of improper assembly. That's why they are staked in the first place.
As I stated elsewhere, when the screws are tightened to the proper torque the screws are nearly at the yield limit for the screws. If the screw yields (stretches) the torque will disappear.
The absence of torque on removal is not positive proof of improper assembly. That's why they are staked in the first place.
I said nothing about the absence of torque on removal... quite the opposite it took a good bit of torque to break through the staking(which was done really well).
The key was LOOSE on the carrier... it rattled and had physical movement up and down on the shank of the screws. The screws were never torqued properly to begin with. And they werent overtorqued and broken either, they both came out whole. Was just a shit install from day 1.
But did you follow the assemble drawing and stake the opposing sides of the screw simultaneously? Or did you run the screw in on one side at a time putting a side force against the unsupported screw head? Just mentioning it since most videos I have seen do it one screw at a time.
I did not. I snugged the four screws up, then tightened them on at a time.
As I stated elsewhere, when the screws are tightened to the proper torque the screws are nearly at the yield limit for the screws. If the screw yields (stretches) the torque will disappear.
The absence of torque on removal is not positive proof of improper assembly. That's why they are staked in the first place.
Isn't the yield limit much higher than 58 in lbs on the OCKS screws?
Isn't the yield limit much higher than 58 in lbs on the OCKS screws?
Nope, they're about the same.
In fact, the ASTM A574, will tend to elongate more under the same load than the actual mil-spec screws.
Nope, they're about the same.
In fact, the ASTM A574, will tend to elongate more under the same load than the actual mil-spec screws.
Are these mil-spec screws? McMaster-Carr- Socket Head Cap Screw (Gas Key) 8-32 x ¼ Part No. 91251A190
https://www.mcmaster.com/91251A190/
I said nothing about the absence of torque on removal... quite the opposite it took a good bit of torque to break through the staking(which was done really well).
The key was LOOSE on the carrier... it rattled and had physical movement up and down on the shank of the screws. The screws were never torqued properly to begin with. And they werent overtorqued and broken either, they both came out whole. Was just a shit install from day 1.
If the screws were loose on arrival from the manufacturer, I would have just sent it back rather than mess with it.
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.
I had two LMT BCG's that the keys came loose. No sealant and the staking was substandard. The screws came loose, causing the gas key to move and wiggle. Called LMT and all they said is that it was a "field fix." Said to tighten the screws and hit them with a screwdriver. The guy I spoke with said I could send them to him, but that's all he was going to do and I would be without my BCG's for a few weeks. I am not much of an LMT fan as I have had other issues with them--which I have posted in the past. IG verified some of my thoughts.
Cheers, Steve
I personally feel that the gasket sealant is important. That is my unfounded opinion, but it makes sense to me on some level. Maybe it's like the moly grease where it's unlikely to matter if you were to skip it, but maybe it's the secret sauce that makes the difference between a rock solid gas key and one that's going to come off.
One thing I've noticed is that loose gas keys often still have the staking in place, precluding the possibility that the bolts rotated. I think loose gas keys fundamentally stem from bad torque spec, and I think part of that is getting a very consistent mating surface. If gas is leaking, the mating surface probably wasn't great, and neither can the torque be. I can't remember the exact procedure, but you leave the stuff to dry for awhile before bolting the gas key down.
At the end of the day I think it's a crap system that needs to be changed in the next iteration, along with bolt geometry. There has got to be something they can do now to improve upon it. Laser welding, I don't know, something to permanently mate those that doesn't require occult knowledge to get right.
There has got to be something they can do now to improve upon it. Laser welding, I don't know, something to permanently mate those that doesn't require occult knowledge to get right.
I may be so far outta my lane I'm about to crash, and being new here I mean absolutely no disrespect but say the gas key is permanently attached, my Daughters cat jumps on my work bench and knocks the carrier off and bends the snout of the key. Instead of a $15 Gas Key and $6 OCKS I would have to buy say a $100 Carrier.
I have some of the Permatex but I got it after I replaced a Gas Key on a Azimuth Bolt Carrier because of my kids Cat & me not paying attention. 🤣
All I did was lap the Key, clean the Bolt Carrier & Gas Key, torque the OCKS & Staked with a punch. That BCG has now ran about 1,200 or so rounds with no problem at all.
P.S I now make sure the Cat is nowhere near my work bench. 🤣
I may be so far outta my lane I'm about to crash, and being new here I mean absolutely no disrespect but say the gas key is permanently attached, my Daughters cat jumps on my work bench and knocks the carrier off and bends the snout of the key. Instead of a $15 Gas Key and $6 OCKS I would have to buy say a $100 Carrier.
I have some of the Permatex but I got it after I replaced a Gas Key on a Azimuth Bolt Carrier because of my kids Cat & me not paying attention. ��
All I did was lap the Key, clean the Bolt Carrier & Gas Key, torque the OCKS & Staked with a punch. That BCG has now ran about 1,200 or so rounds with no problem at all.
P.S I now make sure the Cat is nowhere near my work bench. ��
No it's cool, I knew this was coming, and it's a valid question.
So as you already apparently know, there's a fourth law of nature that says that a carrier will always land on its key, just as sure as toast lands buttered side down.
More often than not it can be fixed. This happens all the time, and it's something that armorers deal with constantly. There's a special tool and instructions in the manual for dealing with it. It's basically just a punch in the shape of the key profile that you just use to beat it back into shape.
Okay, let's say it's so fubar'd you can't pound it back into shape. I've yet to see that being the case, but let's say it happens. You can't just go willy nilly replacing keys. Not only does it require occult knowledge, it requires special tools. A torque wrench for one, and a staking jig. And the application of the sealant and the operation of the staking tool both require some knowledge and skill. Especially the staking is a delicate operation. So you're already looking at a bunch in tools to start with, and you're never going to have confidence in it as an average user because you probably wouldn't do it very well your first time. So you've just spent more on tools than a new carrier would cost and you might still be up a creek.
I've been there. I had to replace a key myself, and I never had confidence in it. It was a beater. I ended up having the same issue again with a Colt carrier, and I ended up just selling it as is to someone who knew enough to be confident in their ability to fix it.
So basically unrepairable gas key damage is rare, and in the event it does happen you're financially better off anyways just getting a new carrier, as replacement simply isn't an end user level maintenance project, at least when it comes to a rifle you need to have confidence in.
No it's cool, I knew this was coming, and it's a valid question.
So as you already apparently know, there's a fourth law of nature that says that a carrier will always land on its key, just as sure as toast lands buttered side down.
More often than not it can be fixed. This happens all the time, and it's something that armorers deal with constantly. There's a special tool and instructions in the manual for dealing with it. It's basically just a punch in the shape of the key profile that you just use to beat it back into shape.
Okay, let's say it's so fubar'd you can't pound it back into shape. I've yet to see that being the case, but let's say it happens. You can't just go willy nilly replacing keys. Not only does it require occult knowledge, it requires special tools. A torque wrench for one, and a staking jig. And the application of the sealant and the operation of the staking tool both require some knowledge and skill. Especially the staking is a delicate operation. So you're already looking at a bunch in tools to start with, and you're never going to have confidence in it as an average user because you probably wouldn't do it very well your first time. So you've just spent more on tools than a new carrier would cost and you might still be up a creek.
I've been there. I had to replace a key myself, and I never had confidence in it. It was a beater. I ended up having the same issue again with a Colt carrier, and I ended up just selling it as is to someone who knew enough to be confident in their ability to fix it.
So basically unrepairable gas key damage is rare, and in the event it does happen you're financially better off anyways just getting a new carrier, as replacement simply isn't an end user level maintenance project, at least when it comes to a rifle you need to have confidence in.
Well I learned something new, I didn't know there was a tool to straighten a Gas Key, I new there was one to straighten out the hole where the Gas Tube goes into.
I also understand about not having or sorta loosing confidence in a part that you have worked on to fix yourself. That Azimuth Bolt Carrier that I fixed, well I lost confidence in it until I got a good 400 to 500 rounds back on it. Once I had put around 1200 rounds on it I took it out and put in a new BCM BCG and now use that Azimuth BCG for a spare.
Well I learned something new, I didn't know there was a tool to straighten a Gas Key, I new there was one to straighten out the hole where the Gas Tube goes into.
I also understand about not having or sorta loosing confidence in a part that you have worked on to fix yourself. That Azimuth Bolt Carrier that I fixed, well I lost confidence in it until I got a good 400 to 500 rounds back on it. Once I had put around 1200 rounds on it I took it out and put in a new BCM BCG and now use that Azimuth BCG for a spare.
Well if it's a good install, it's a good install. If it's not, then there's no round count at which that changes. If it's not, it could go at round 1 or round 1 million, or anywhere in between.
There is no tool to straighten a gas key, just to reform the opening. I've never seen a gas key get bent in that way though. That would take a lot of force. I dropped one from chest height onto concrete, and it didn't bend. If you manage to bend one, I guess that's just an SOL kind of day, and you would just have to bite the bullet and buy a new carrier.
Replacing a gas key is a competent armorer level task.
https://youtu.be/GCFAtcV1c8k?t=484
Well if it's a good install, it's a good install. If it's not, then there's no round count at which that changes. If it's not, it could go at round 1 or round 1 million, or anywhere in between.
There is no tool to straighten a gas key, just to reform the opening. I've never seen a gas key get bent in that way though. That would take a lot of force. I dropped one from chest height onto concrete, and it didn't bend. If you manage to bend one, I guess that's just an SOL kind of day, and you would just have to bite the bullet and buy a new carrier.
Well no wonder I never seen that tool then 🤣 my bad. I have seen the tool to reform the opening but I am either OCD or just crazy, if the opening was to get outta wack I would just replace the key.
My work bench is a little higher than most but not that much. Anyway when it fell off it hit a small vice. Well looking at it you couldn't tell if it was bent, or I couldn't, but what I did to notice it was bent was to take and strip it and slide it in the upper receiver, when it got to the gas tube you could see the tube move and fill it bind just a touch. I reckon I could have bent the gas tube down but I had a couple extra gas keys so I just changed it.
The way it hit on the key it sprung it somehow. I have read that Azimuth BCG's are supposed to be good to go but at the time I didn't really know that, actually I still dont know it honestly, I just read it somewhere so I eventually just swapped it with a BCG I knew was good.
Well no wonder I never seen that tool then �� my bad. I have seen the tool to reform the opening but I am either OCD or just crazy, if the opening was to get outta wack I would just replace the key.
My work bench is a little higher than most but not that much. Anyway when it fell off it hit a small vice. Well looking at it you couldn't tell if it was bent, or I couldn't, but what I did to notice it was bent was to take and strip it and slide it in the upper receiver, when it got to the gas tube you could see the tube move and fill it bind just a touch. I reckon I could have bent the gas tube down but I had a couple extra gas keys so I just changed it.
The way it hit on the key it sprung it somehow. I have read that Azimuth BCG's are supposed to be good to go but at the time I didn't really know that, actually I still dont know it honestly, I just read it somewhere so I eventually just swapped it with a BCG I knew was good.
It's highly likely that it just slightly deformed the opening. It doesn't even have to be enough to see with the naked eye to cause it to bind like that. You know that opening is chamfered, so it leaves an extremely thin and easily deformed edge. You drop it, it's probably going to land directly on it because of the weight distribution, and it doesn't take much. It's no biggie to just reform it with the right tool, though. All that matters is that it doesn't bind on the gas tube.
It's highly likely that it just slightly deformed the opening. It doesn't even have to be enough to see with the naked eye to cause it to bind like that. You know that opening is chamfered, so it leaves an extremely thin and easily deformed edge. You drop it, it's probably going to land directly on it because of the weight distribution, and it doesn't take much. It's no biggie to just reform it with the right tool, though. All that matters is that it doesn't bind on the gas tube.
Ya know that was probably what happened and I thought it bent the whole thing. It was sorta hard to tell because it wasn't moving the the Gas Tube from side to side, it was pushing it down.
Ya know that was probably what happened and I thought it bent the whole thing. It was sorta hard to tell because it wasn't moving the the Gas Tube from side to side, it was pushing it down.
It's a very tight fit, and that rim is super thin. It only takes a tiny little ding to deform it enough to bind up. Probably makes sense for any AR enthusiast to have one of those punches around just in case. It's not hard to do.
It's a very tight fit, and that rim is super thin. It only takes a tiny little ding to deform it enough to bind up. Probably makes sense for any AR enthusiast to have one of those punches around just in case. It's not hard to do.
I'm gonna see about getting myself one of those punches, if I don't ever need to use it one of my friends might could.
I'm gonna see about getting myself one of those punches, if I don't ever need to use it one of my friends might could.
True that man. Anybody who's ever dropped buttered toast is in the at risk category. Now that I think about it, I'm not sure why we don't just have one in our range bags along with broken shell extractors and bolt pry bars. All you need besides the punch is a square piece of wood and something to hit it with. If you can find a fence post and a rock it's something that could hypothetically be fixed in the field.
Anyone know where to get one and how much they cost?
Anyone know where to get one and how much they cost?
No Sir, I don't not yet. Soon as I do I will post about it.
No Sir, I don't not yet. Soon as I do I will post about it.
Thank you Spooky.
Thank you Spooky.
Your welcome.
Does whacking a gas key with this repair tool not compromise the screws or the seal or whatever? Would this tool be in the collection that DoD armorers have?
Does whacking a gas key with this repair tool not compromise the screws or the seal or whatever? Would this tool be in the collection that DoD armorers have?
You brace the key itself on a bench block. The tool is in the manual, but I don't know if it's something they currently do or not. Might even depend on the armory. I suspect some just throw them away, because I've seen carriers with fubared keys trickling out of military bases on Armslist.
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