Gypsy, thanks for the gen1/ gen2 description. I have the Gen 2.
A comment I have at this point is that I screwed in a Remington 870 muzzle brake, and although it threaded in, there was an aesthetic gap left, as if the muzzle brake couldn't be screwed in quite deeply enough. The gap doesn't allow for any void/ space where air pressure could escape, so the muzzle brake still functions fine. Not surprisingly, it did work itself loose, without any Loctite.