In the Army we used a high temp silver colored anti-seize on the tank exhaust grill door bolts. That stuff works good on threads and holds up good to high heat. Might be good on AR barrel installation. Anyone who has walked behind a running Abrams tank knows the heat it puts out. I've seen them start grass fires. I saw one pivot steer in a circle in the middle of a riot to clear everyone out when they were blasted with exhaust.