The Loctite people specifically recommend red Loctite for fasters 3/8" to 1" in diameter. Most screws on an AR are much smaller than that, so red Loctite really has no use on an AR. Using red on small screws leads to stripped or twisted off heads.
I use blue Loctite on all of my optics and rail mount clamps on my AR. The manufacturers of the mounts and BUIS I use either include blue loctite in the package, or specify it's use as well as torques for the fasteners.
When dealing with BIG bolts, an impact wrench or cheater bar is all you need to break red loctite.
