I keep seeing conflicting answers online about which anti seize to use for the threads on the upper receiver on an AR-15 where you tighten the barrel nut down. What is the best anti seize to be using on these? I have heard not to put copper on aluminum and some of these compounds are copper based. I also see silver, nickel, and other various stuff that people are recommending. Which is best? I am using a 10.3 Ballistic Advantage Barrel made from 4150 chrome moly vanadium steel with a QPQ finish and it also has a nickel boron coated barrel extension. Thank you.
Bought my tube of aeroshell almost a decade ago and it’s still 99% full. I use a pinhead amount on suppressor threads as well along with anything else that gets gritty and squeaks over time (garage door wheels, door hinge pins, etc…). Also used on my BMW GS splines (call for moly grease).
You can buy Aero Shell grease online, just do a quick Google search. I found a tube at an online airframe repair supplier. I don’t think I’ll ever use it up in my lifetime.
Aeroshell 33MS. Graphite is the one you want to avoid. 100% copper is okay and some manufacturers prefer it over the Aeroshell for some reason, but it theoretically changes the amount of clamping force from the specified torque using milspec components. Whether it’s enough to matter or not I don’t know. If you were at the extreme low end, maybe. I would just use the Aeroshell, though, especially since you can buy it in little five dollar doses, whereas a jar of 100% copper will set you back about thirty bucks. Well, any of them will set you back about that much, and a tiny little dab will do you. So again, just buy the little tub of Aeroshell and be done with it. And not have 29 dollars worth of unused grease sitting in your garage for decades that your kids will throw away when you die.
I ordered some Aeroshell 64/33MS from a company called Umbrella Corporation. How much needs to be applied to the threads on the upper receiver? And should I place some inside the upper where the barrel extension goes into?
First make sure the threads on the upper, and barrel nut are clean. Apply an even coat to both the barrel nut threads, and the receiver threads. I also apply an even coating on the barrel extension before I slide it into the upper. After torquing the barrel nut, wipe off the excess grease with a clean lint free rag.
There are only 2 places where the lube absolutely needs to be and that’s on the threads of the upper receiver and on the forward/FSB facing side of the barrel extension flange (the side opposite of the indexing pin).
I’m not sure why covering the entire surface of the barrel extension before sliding it into the upper became a thing, but it’s completely unnecessary.
And the “only a small dab will do ya” will not give best results… Apply liberally, it’s really the only liberal thing I can recommend doing.
I prefer the lube Colt uses (MOLYKOTE G-N Metal Assembly Paste) over the AeroShell 64/33MS, but I actually use T.S. Moly’s TS-70 moly paste for barrel nuts.
For most builds, just the threads are necessary for torque value in my opinion. I say this because galvanic corrosion is probably not very common on civilian owned ARs. I have put some on the outside of the barrel extension on tight fits so I can get it apart if I even have to without boogering up the gun.
It was many years ago that I noticed guys smearing moly grease all over the barrel extension, this was being shown in YouTube videos showing off the process of barrel installation. For the most part it seemed like the guys in the videos were doing this for the first time and really had no idea where to put the grease so they just put it everywhere. I really think it took off from there.
I typically avoid thermal fit uppers, but the A2 upper I just installed a barrel on had that as a feature. If I ever have to take it apart and run into an issue because I didn’t smear grease all over the barrel extension I will report my experience with it.
