[lugerholsterrepair]

Don, I started with one reason and I remain a supporter of it. Several other reasonable theory's have emerged..That the disc is a visual cue cannot be doubted or discounted. That it is highly reflective supports my position. If it were meant to distinguish one era of magazine from another has no merit for a couple of reasons. A visual cue of that small degree requires no reflection. Just a muted color would suffice. Paint of almost any light color would do the trick. A highly reflective metal disc..was for an altogether different use.
Secondly..if German magazines were defective enough to be distinguished from Swiss..they would more likely be discarded or sold.
Nope..No other reason for this disc.
But I have had my say. I won't go on and on trying to convince anyone. If I have not made my case by now.. I never will.