Gunsmithing installing ar 308 barrel

[Deerhunter]

Any paste or compound needed for an accurate build? Ive seen a lot of people only use loctite on the barrel receiver. My barrel without anything fits pretty tight already. What is the procedure for the top end smiths?

 

[sentry1]

The smith I give my AR to (who also happens to shoot a lot of competitions with his own rifles, AR & bolt) uses loctite around the barrel extension, and an anti-seize on the threads (that's just so it doesn't gall, I doubt there's any performance bonus there).

 

[Deerhunter]

Thanks brother

 

[Nutro]

My brother has probably installed 200 barrels for us and friends and he uses some kind of expensive grease on the receiver threads.

 

[elephantrider]

AeroShell Grease 33MS is the correct grease/anti-seize for the upper receiver threads. It should be applied to the upper receiver threads, the inside of the barrel nut, and the small flat surface where the shoulder of the barrel extension and inside of the barrel nut meet. It is sold in large tubes by aviation supply companies or you can get a small jar that will last many, many barrel installations here:
https://www.ucwrg.com/materiel/weapon-lubrication/18/aeroshell-33ms-grease/

 

[tarfu64]

If the upper to barrel fit is loose, I use stainless shim stock (.001) on the barrel extension and Loctite 640 to hold everything together. If the fit is fairly tight, I still use just the 640 to hold everything in place. I also face the upper to square everything up.

There are many ways, as it is with everything, to skin this cat. This is how I do it in my shop, and I have had pretty good results. Taking it all apart to replace the barrel can be a bit of a pain, but rare is the client who shoots so much that the barrel is shot out.

Just about any anti seize works fine on the threads. I've used everything from moly grease to regular anti-seize, just as long as something is there to prevent galling. I really don't have a "favorite".