On two different occasions. Once while coyote calling I was in a fence row and was just starting a call series and I spot a coyote way, way out in front coming toward me. I flip off the safety and start to wait. I then notice a coyote coming from my hard right about 30 yds away. It had not made me yet so I eased the gun over and dropped it. I hurriedly work the bolt (as in short stroke) and scan for the first coyote. Surprisingly it is still workng it's way to me. I wait until it is about 50 yds. out, put the cross hairs on it's chest and bark it to a stop. Click! I had worked the bolt so fast after the first coyte that I did not get the empty ejected and dropped the hammer on a fired round. I worked the bolt again but the coyote had made the brush by then. No double that day.
The other occasion was group hunting many years ago during shotgun deer season. The previous day's hunt had ended in sleet and snow. I so tired after the days hunt that I did not take the time to properly dry the action of my pump shotgun. I assumed taking it out of the case was good enough to dry it out.
This day's hunt dawned bitterly cold and very windy. I was elected to be a blocker because of the cold. I was dropped off on a fence line at the end of a draw. I jumped over the fence and went to load my gun. The action had frozen open by that time. I could not get the bolt to close no matter what I tried. As luck would have it several deer came right down the draw I was on and trotted right past me. One of the other hunters was in sight of me and came over after and asked why I did not shoot. Needless to say I was the butt of many jokes the rest of the day.