I used to blow off a 20 gauge to stop barkers at night. It doesnt seem to affect most of my dogs. Sometimes for whatever reason a dog doesnt like loud noises i.e thunder, cars backfiring, hammmering or gunshots. My mom has an APBT that is out of our old line. Hes fearless on a hog or whatever but hell run and hide at the first loud noise. A blank pistol helped the slower learners I had. Also work with giving em voice commands to "back up" or "come outta there". My old man dog now when I tell em to "come outta there" run straight to my feet until the shot then hell go straight back to the hog. Its not too hard and ive been lucky with smart dogs that make me look good.