I guess my biggest blunders have been with bows.
I used to shoot fingers, then I cut the tip of my finger off so that particular year I switched to a release and was getting used it. But one evening I had a really nice bull elk come out in front of my blind I had set up in some pines. When the cows all came through the bull followed and was about 30yds away from me broadside. I had drawn my bow back and was waiting of him to clear the trees. And when he did I had the pin right on his heart area and opened my fingers to shoot. Nothing happened. Then I flustered my self and hurried up trying to get back on the trigger of the release and hit it before I was back on target and sent the arrow right under him. He kicked his legs out in front of him but he never got touched. I got humbled pretty good.
I have another that worked out in the end. My first deer hunt as a child. Three deer standing together. My father said to shoot the one in the middle he's the biggest. Buck fever had a hold of me so bad I jerked the trigger so hard I hit the one on the right in the neck. Of course the deer was killed instantly but I trully missed my deer.