I'm guessing you mean other than hunting.
I have had to use a firearm to defend myself a couple times.
The most memorable was walking a trail at a large campground/state park ... coming around a blind corner ... and startled a bull elk grazing right next to the path. I backed around the corner, but he came onto the trail ... saw me ... lowered his antlers and stomped, preparing to charge. So I drew and fired in the air. (I knew I wouldn't kill him with a handgun. Just make him mad.) He paused long enough that I was able to retreat around another corner. Luckily, I guess he decided to go back to his meal.