And do I really need to use anything ? I put a muzzle brake on one of my ar's without any goop and can't imagine that thing ever coming off without a clamp and wrench.

 

I would use only a bit of anti-seize and the lock nut.

 

^ This

 

I haven't tried it for this application, but Rocksett has a temp resistance to over 2000F (although they don't tell you what the strength is reduced to at that temp) whereas the ultra high temp loctite 2422 or 2620 has a temperature resistance to 650F. And temperature is the issue with a firearm barrel. So this is likely the reason most guys use Rocksett.

 

Rocksett is definitely the choice because of temps. I would use it especially with a brake with a jam nut because of the increased opportunity for movement. If you were timing it with shims then probably no thread lock of any kind would really be needed.


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How hot are you realisticaly going to heat your barrel?

Rocksett is high heat, but not high torque-- other thread lockers are higher torque but not heat resistant. Pick your situation. Since you are using a jam nut, then go with the Rocksett, which will cover all your bases.

 

Thanks for all the replies. Got the Loctite today and it says for temps up to 300 so that's pretty worthless on a rifle barrel. Probably gets about 150-200 just sitting in the sun on a shooting bench. I think I'm going to go with just the nut and if there's ever any movement just add some rocksett or anti seize if needed.

How hot are you realisticaly going to heat your barrel?

Wellllll, I've gotten an ar barrel literally red hot. If you spend an extended amount of time on the range, have multiple people shooting the gun, shoot a little full auto and/or do a couple mag dumps, you can easily get the barrel VERY hot.

 

Then you should really consider using the Rocksett, since it has been proven that lockwashers, and "jam nuts" do not work as well as thread lockers, due to the differential expansion of the metal parts.

 

due to the differential expansion of the metal parts

For some reason that amused me