What do you put on barrel extensions?

[556Cliff]

Curios about something here. MolyKote has an expiration date on the tube. Mine is currently 2/25. Does it only expire unused inside the tube lol? Or if its installed on your barrel nut a month before expiring and the gun sits inside the safe and it expires after wiped on a barrel nut? No I haven't been drinking and I am serious.

Does aeroshell have a similar expiration date?

I believe all greases/pastes have an expiration date even if it's not listed on the container. The one I use also has an expiration date (the TS-70 Moly Paste). I had to email T.S. Moly about it since there is no expiration date on the label. About 2 years stored in inside the house conditions.

I had a container of NECO Moly-slide paste thicken up and go bad on me after about 10 or so years.

I think as long as the grease is in good condition on installation of the parts that's all you can hope for. Going to disassemble things years later I've heard that the moly can be kind of gummy. Actually, the A1 "clone" I took apart at the end of last year came apart easy enough, but the grease did seem much thicker than it was when I installed that barrel nut back in 2016 (if I remember right).

At this point I probably need to go through all of my old containers of Moly grease and check them out to see if I need to get rid of any of them.

Having said that, I think as long as it still mixes up good and has a consistency that still resembles how it was when new then it's still probably good to go. Though I could be wrong as I'm no grease expert.

[jsbhike]

If i am understanding you correctly, the Loctite variations you are referring to are for cylinder fits and come from National Match type shooting disciplines to more or less make the barrel extension and upper 1 piece. The other part of that really has to be the upper's inside diameter being smaller than the outside diameter of the barrel extension requiring the upper to be heated to expand enough to accept the barrel extension.

Originally that was done by wrapping shim stock around the barrel extension to increase the OD, then some barrel makers started using oversize OD barrel extensions, and now some upper companies(BCM is one) making undersize ID uppers usually advertised as thermal fit.

Another part of that is cutting the receiver face to square/true it up going on the assumption the shoulder of the barrel extension is more apt to be square and true than the corresponding face of the upper where the barrel enters.

Grease specified in the armorers manual is the blend in Aeroshell 33MS, although there are others.

I think the biggest thing is avoiding greases that use graphite due to the possibility of galvanic reactions from aluminum and graphite(and recall reading a Navy memo that graphite and steel can have issues too).

[Todd.K]

I think the biggest thing is avoiding greases that use graphite due to the possibility of galvanic reactions from aluminum and graphite(and recall reading a Navy memo that graphite and steel can have issues too).

This is the reason moly grease is specified.

A little on the threads and make sure the front of the barrel extension has some grease all the way around where the barrel nut has to rotate against it.

Torque well above minimum and then loosen several times, then torque to minimum and tighten to the first notch.

[ndmiller]

Bought a canister of Aeroshell a decade ago and have used maybe 2 fingertips from it, should last forever.

[the AR-15 Junkie]

Bought a canister of Aeroshell a decade ago and have used maybe 2 fingertips from it, should last forever.

The Certificate of Analysis will be reflected to state: “Shelf life of AeroShell Grease is 6 years from the date of manufacture.

[tangolima]

I degrease OD of barrel extension and ID of the upper. Blue loctite is then applied to "bed" the barrel extension to the receiver. Its effectiveness is questionable, but why not? Grease is then applied to the threads. I just use normal grease. It is to minimize the friction so that the torque is thread to thread reaction, rather than to overcome frictions.

Galvanic reaction is already going on between steel and aluminum parts. Graphite could make it worse as it is pretty positive in galvanic index.

-TL

Sent from my SM-N960U using Tapatalk

[bamashooter]

I pack the CVs on my axles with red and tacky, good stuff.

On my AR I use something that is silvery grey, it appears to have metal powered in it? It was sold specific to barrel nut use

The AR stuff you refer to sounds like basic Permatex anti-seize.

[One More Time]

The Permatex moly paste I use on some head bolts is a silver gray color, anti-seize is more of a silver color. It's a low friction, non metallic lube.
I use it on barrel nuts as well.

[e z money]

In the Army we used a high temp silver colored anti-seize on the tank exhaust grill door bolts. That stuff works good on threads and holds up good to high heat. Might be good on AR barrel installation. Anyone who has walked behind a running Abrams tank knows the heat it puts out. I've seen them start grass fires. I saw one pivot steer in a circle in the middle of a riot to clear everyone out when they were blasted with exhaust.

[1168]

Using antiseize will increase removal torque vs grease for a given installation torque, I think. Anecdotally, that effect seems more significant on threads larger than 5/8” in diameter for some reason. Maybe one of our engineers can illuminate this topic better.

I don’t think I would call moly lube non-metallic, but I also don’t know if it matters.

As for what I use, that’s Lubriplate SFL-0, simply because it’s what I have laying around. I think it’s aluminum or lithium -based. I’ve been using it for several years and haven’t noticed any problems throughout the service life of my barrels, and they don’t give me any drama when I swap them out. Hopefully this isn’t the wrong answer.