It might be a clue that the usual thread locking compounds weren't invented until about 1953. And whilst the Japaneseicon did have some leading edge materials science applications during the 1930s (the 7000 type series of aluminum for example, first seen in Zero fighters, I'm pretty sure!), I would expect if they did such shenanigans in building up the take down rifle, they would have used solder or braze. But I can't think of why!