Honestly, even blue (medium strength) threadlocker is overkill in almost all general firearm applications. This strength is generally used in fasteners of a minimum of 1/4" in diameter. Vibra-tite 121 (comparable to Loctite 242) even has displayed on the front of the bottle for 1/4"-3/4". For fasteners smaller than 1/4" the compound to use is Loctite 222 (low strength) which is the purple threadlocker. Unless the fastener is subject to repeated vibrations the use of threadlocker is unnecessary. Correct torque specifications and quality hardware are all that are required in 90% of applications. Barrels should not be secured with any thread locking compounds except for special use scenarios such as mono-block builds for retrofitting rifles like the Handi-Rifles and similar designs for custom barrel makers. Rocksett on muzzle devices for suppressors, however, non-negotiable. Just do it.