TAC has it, of course.
Look very carefully at your gun and cycle a dummy round through it very slowly. Then cycle a casing through it, slowly.
The EXTRACTOR grips the Rim solidly and pulls the casing backwards, out of the Chamber. As the casing is backed over the EJECTOR, the Ejector contacts the casing near its BASE, forcing the Casing to ROTATE out of the grip of the Extractor. The Casing then flips UPWARD and out of the action, but it still is rotating. As a result, it beats its open mouth against the top of the Breechblock, rebounds from that and flips up and over you, generally landing on the ground a pace or so behind you.
This mystified me after I got my first Luger, many years ago. I now have three of the beasts and they all do the same thing. If you fire your Luger a fair bit without cleaning the top of the Breechblock you will, after a time, notice a faint gold appearance where the brass has been bouncing. This cleans off easily; most people never notice it.
Exactly the same parts in the same alignment are what cause the MG-34 and MG-42 to beat the mouths of their brass so badly although, in their case, the brass is banging off the Triggerguard just ahead of your finger. MP-40, on the other hand, wants to stack the brass just behind your right boot.
The GOOD PART is that, generally, you don't have to hunt all over the range for your brass!