One of the weirdest gun incidents I ever experienced was with an Automag. A friend was shooting his when it jammed. The round from the magazine would not go in the chamber. We checked the usual things (cartridge, chamber, etc., and saw nothing wrong. Then I looked through the barrel and it was blocked. Thinking he had a stuck bullet, I used a cleaning rod to see if the obstruction would come out, and it did. It was the case of the last round he fired, and it was in the chamber backward! That accounted for the fact that the chamber appeared to be empty.
As best we could analyze the "problem", the gun fired, then the recoil caused it to catch up with the ejected case, which then somehow entered the chamber base first.
Had anyone told me that could happen, I would have been very skeptical, and I would not be too offended if some folks think I am drawing the long bow here, but it really did happen!
Jim