AR15/M16 barrel installation.


August 8, 2004, 02:33 AM
When installing an AR15 or M16 barrel, who uses what on the receiver threads for the barrel nut?
I've heard and read grease or anti-seize.
Derrick Martin in "The Complete Guide to AR15 Accuracy", pg. 115, uses Loctite 242.

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Badger Arms
August 8, 2004, 03:07 AM
You don't use anything on the threads. Torque it down to the specified value (can't recall, look it up). Once you've done that, loosen it and torque it down again. Repeat this procedure one more time and then back off till the upper lines up so you can get the gas tube through. That's it. Won't back off, no need for anti-sieze or locktite.

August 8, 2004, 03:34 AM
Molybedium Disulfide grease is the ONLY thing to use. Available at Auto Zone for less than $3 for a tube(grease gun style).

Don't ever use Loc-tite for that application.

Don't do it "dry" if you ever plan on replacing the barrel on the upper receiver.

And go to and lurk around for answers to all your AR questions.

August 8, 2004, 03:50 AM
I was planning on using MolyDi grease.
Rifle will have a 20" government profile barrel, flat top upper, and Cavalry Arms MKII lower.
I think Martin using Loctite is more for Match type rifles where security and no movement is a concern. I recall seeing elsewhere where some shooters replace the upper and barrel together, maybe due to Loctite?

Have been to and read some debates about barrel torque.
I plan on screwing the nut by hand, then line up the hole using a wrench. Done this once before with good results, and seems to be the preferred method at and with some other names in the business. I won't use the triple torque method.

August 8, 2004, 04:00 AM
The spec is 35 to 80 foot pounds IIRC.

Torqued mine(using the grease) to 35 then backed off--------reset the wrench to 80 and hit it again till the spaces lined up---the wrench never broke at 80-----so I'm definitely over 35 and less than 80-----she shoots like a champ BTW.

Don of Kalifornia
August 8, 2004, 09:14 AM
I'd use anti-sieze, as the problem putting the threads together dry, is the threads will gall, making the upper useless to ever try to install another barrel on. even worse is the threads may gall before fully torqued causing thread failure and then needing to replace the upper and maybe the barrel nut.

As years as a mechanic, you never put threads together on aluminum with out anti-sieze or at least a moly- based grease.

August 8, 2004, 11:31 AM
If you send me an email, I will Check with our AR guy and let you know (ex military match armorer who has built about 350 ARs for us)..

Dont use Loctite.

Dont think you have to loosen or tighten


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