These days I�m pretty successful and kill one each year. It wasn�t always like that.
I could fill a book with my mistakes and the book would still be growing larger. I�ve probably formed a mental block on my very worst ones but these were some doosies.

Laid the crosshairs on the biggest bull I�d ever seen while holding a bull tag. Long but thin 6x7 antlers. �Click�. It was a sickening sound. I had been distracted when leaving the trailhead � too worried about making sure the younger hunters were set up properly and not paying attention to my own stuff. Not only was the chamber empty but the gun was unloaded! That bull was just unlucky. I somehow managed to fish a round from my pack, chamber it, and it found it�s mark.

Two nice bulls skirted the edge of a clearing I was hunting. I passed on a long shot because I knew my Dad and Brother were coming in from the other end of the clearing. The bulls walked straight into the ambush. I waited for the shot, � and waited. Nothing.
When I saw them later they said they decided to go another way.

Killed a cow on a steep grade. Since I was sure of my location I began dragging it downhill toward the trail. I was pleased with myself to have the cow right in the middle of the trail in one piece. It was the wrong trail. I ended up having to quarter it and hump it back up the same hill I�d just descended to get it back onto the correct trail.