I don't know, in my latter case I never found the damned thing to inspect it.Before that, yeah, blue Loctite didn't hold, the screw loosened, and I was bending the Allen when tightening it down.
From what I gather, people may not be making sure the set-screw is in the lowest point of the concave area of the front of the charging handle, then if it moves at all & the set screw is at a lower point, there's no pressure on the set screw, so it can work loose & fly off.
Who knows, maybe they're simply pushing it on as far in as it can go & reefing on it, but just a slig