I've heard that after copious amounts of Vitamin "B", that one could forget that the firing pin detente lever in the frame of Colt Mark IV/Series 80 needs to be down in its slot or recess when installing the slide back onto the frame. Otherwise, the slide will not move into position for the slide stop pin to be inserted, and the owner will repeatedly slam the slide back trying to get it into the correct position, and in doing so, the lever nose/arm will become bent and eventually - a few years later - fracture and fall off. Then, the gun won't fire. Or so I've been told, anyway. No ammo need be involved. Just the gun owner and copious amounts of Vitamin "B".