Alexvs The flow control disk would have reacted a bit like those USA spinning hub caps…the screw might have popped out and partly passed through the cutout in the flow control disk…which wouldn’t have been fantastic. The burrs would still turn, because the black bit under the disk has a piece of metal that engages in a keyway.
The sweep arms would probably not sweep much because the middle burr wouldn’t have been tight down on them to create the friction required for them to turn.
Moral of the story…check the middle nut occasionally…if it was that loose, then you should find a great increase in dose consistency and chamber clearance 🤣
I have always wondered if there was a way to warn the user if it was loose (like those valves with Tyre indicators), but I think it would be too difficult….the other thing I have thought about was a very low break torque thread lock…but I would worry about buildup in the base of the screw thread hole preventing full tightening.
Pro Tip One thing you can do of course…..make a black sharpie mark in line with the middle of the hole in the flow control disk (or a white mark with a chalk pen), or inline with the C in Niche…if that ever moves…then it’s loose