A while back I bought a 40lbs box of mixed range brass from Everglades Ammo. Price was so good I just couldn't pass it up. Turns out I found three 9mm cases that had been fired out of a 40 so apparently it happens more often than we might think.

A few months ago I was shooting with my father-in-law. He was shooting one of his 1911's when one round made a rather strange sound more like a shotgun. Turns out he had mixed some 40's and 45's together and loaded and mag. While it did fire the 40 round it did not cycle the slide and the case was lightly stuck in the chamber. Other than having to remove the stuck case no harm was done and hopefully a lesson was learned.