Barrel mounting consensus This vs That

[HANSEL AND GRENDEL]

I am about to mount my 2nd barrel. My first barrel was a remount to add a free floating hand guard and I used high temperature grease on the barrel extension and threads. Since then I have read about using Loctite 620, Loctite 609, or high temperature grease on the barrel extension and blue, green, or red Loctite, anti-seize, or high temperature grease on the threads. I understand there may be specific reasons for each, I am just looking for a good middle of the road combination for normal circumstances. Any help would be appreciated. Thanks!

[VASCAR2]

I use blue Loctite on the barrel and the inside of the upper receiver to give a solid fit. I use anti-seize on the barrel nut threads and would not use thread locker on the barrel nut. If torqued correctly I don?t think thread locker on the barrel nut is needed. You?ll get a lot of opinions but fortunately my barrels fit the upper receiver tight enough, I never needed shims or needed to freeze/heat either component

[HANSEL AND GRENDEL]

I use blue Loctite on the barrel and the inside of the upper receiver to give a solid fit. I use anti-seize on the barrel nut threads and would not use thread locker on the barrel nut. If torqued correctly I don?t think thread locker on the barrel nut is needed. You?ll get a lot of opinions but fortunately my barrels fit the upper receiver tight enough, I never needed shims or needed to freeze/heat either component

Thanks!

BARREL EXTENSION

Blue Loctite - 1
Loctite 620 - 2
Grease - 1

BARREL THREADS

Anti-Seize - 1
Grease - 1
Dry - 1

[ricsmall]

I use loctite 620 bearing mount adhesive. I think that’s the new designation for the old 680. It’s designed to fill up to .010” gap and has worked well for me. On the threads I use a moly grease.

[Popeye212]

Just did a barrel remount with the 620 and lapped the receiver on my Sport...did well. Also took the crush washers off all my AR's and used the washer system and it seems to have helped.

[Klem]

If it's a tight fit you won't need to fill the voids with glue. I use Castrol CMM (high temp/high pressure moly grease). With proper torqueing of the barrel nut it won't come undone.

[FLshooter]

I go out to the garage and get a dab of black molly grease and lube the barrel extension.Then I put the barrel nut on dry and torque to 40 Ft lbs.That’s it.No need for any thread loc.My buddy builds and repairs AR15 all day every day.He’s done 1000’s like that.Never an issue.So,that’s how I do mine.

[A5BLASTER]

I go out to the garage and get a dab of black molly grease and lube the barrel extension.Then I put the barrel nut on dry and torque to 40 Ft lbs.That’s it.No need for any thread loc.My buddy builds and repairs AR15 all day every day.He’s done 1000’s like that.Never an issue.So,that’s how I do mine.

You need to go buy a lottery ticket.

No lube on aluminum to steal threaded connection is a big no no in every industry not just the gun industry. Sooner are later it's going to bite you in the butt hard.

[Lastrites]

I go out to the garage and get a dab of black molly grease and lube the barrel extension.Then I put the barrel nut on dry and torque to 40 Ft lbs.That’s it.No need for any thread loc.My buddy builds and repairs AR15 all day every day.He’s done 1000’s like that.Never an issue.So,that’s how I do mine.

Surely that is just a typo, that's just not how these things are supposed to be done.

[FLshooter]

You need to go buy a lottery ticket.

No lube on aluminum to steal threaded connection is a big no no in every industry not just the gun industry. Sooner are later it's going to bite you in the butt hard.

You need to read my post again. It says barrel extension. I install the barrel nut dry.When I took my Colt 6920 factory barrel off it had Molly grease on the barrel extension.

[FLshooter]

Surely that is just a typo, that's just not how these things are supposed to be done.

By all means,tell us how it is supposed to be done!

[Klem]

I can see where FL is going with this.

Yes, dissimilar metals are a recipe for galvanic corrosion but they have to be in intimate contact and usually something to aid conductivity like water, or worse, salt water. Anodising on the aluminium upper acts as an insulator however so unless this coating has been worn off at the time of fitting, like if the mouth has been squared beyond the black anodising then galvanic corrosion is a non issue. Plus, if he occasionally cleans and we all use oils for that, and he's not getting it constantly wet or working out of the ocean then all is well. In fact, put too much glue or grease on the mating surfaces and in such a tight fit could work against a nice solid join. You don't want your barrel nut squashing a big goop of grease or glue up onto the shoulder as the extension pushes in. Like galvanic corrosion this also might not be an issue but I would prefer not to tempt fate with a nice square contact.

That said, I run a greased cloth quickly around the inside of the mouth and outside of the extension before fitting. So fine you can't even see it. Moly is going on the threads anyway so I figure a super fine coat aids it going in, and out again when it's time to change barrels.

[A5BLASTER]

You need to read my post again. It says barrel extension. I install the barrel nut dry.When I took my Colt 6920 factory barrel off it had Molly grease on the barrel extension.

No I read it correctly the first time. You said you put grease on the extention and torque to 40 foot pounds.

The grease goes on the treads. Steel and aluminum threads never go together without a lubricate. Doing so is just asking for a seized up thread attachment and results in a ripped off thread and a ruined product.

[FLshooter]

No I read it correctly the first time. You said you put grease on the extention and torque to 40 foot pounds.

The grease goes on the treads. Steel and aluminum threads never go together without a lubricate. Doing so is just asking for a seized up thread attachment and results in a ripped off thread and a ruined product.

I understand what you are saying.I may install the barrel nut dry and no loc tite.But I?m sure that plenty of lubrication has penetrated the metal surface of the threads by the time I?ve lapped the face of the upper receiver and cleaned it w/CLP and wiped it off.I have never and will never have a problem with any barrel nut seizing and ripping off threads.

[aephilli822]

How about good ole Garand grease pot grease?