[HisSoldier]

A round which is not delayed that microsecond through heat adhesion may be bulging as it is coming out of the chamber. Firing a 30 Luger in a 9mm chamber would cause a gas bubble behind the bullet at the area where the cartridge is necked down, forcing the round out of the chamber sooner than the complete burning of the propellant

No offense, but I have trouble believing that, I've seen P08's with 16" barrels, which (It seemeth to me) should have more left over pressure than a normal or 6" barrelled gun, although it's also possible that the gas expansion down a 16" barrel might be enough of a drop in pressure to keep cases from bulging. The unknown, for me, is how much pressure remains from a .30 Luger round at the moment the action begins extraction (The actual releasing of the locking). The cartridge cannot come out until that moment. I hope I didn't come across too harshly, I've been too wrong too many timer to think I'm always right. Either that or you are describing something else?
It looks to me like range brass that someone fired in a 9MM chamber, I'm guilty of that myself! I bought a CZ 24 once, I couldn't get .380 rounds in the mag and (Silly me.) I assumed that they must have made some CZ 24's in .32, a whole magazine and I can barely keep the rounds on the target at 10 feet! I look at the cases at my feet and they looked like that, turns out the former owner sent me a magazine from one of his CZ 27's. Went right over my head to check the chamber and exit bunghole. The magazine fit perfectly of course.