Better go for multiple rounds of # 4 Buck and distance to make a hit on the critter running AT you. I can tell you the hardest thing to hit is a pup determined to get a bite on it’s target......
Short of the 12 gauge feed the dog your weak arm as ya draw your gun or knife with the other. Empty the mag into the damn thing or keep cutting /stabbing until it is dead....
Anything else is dangerous per my experience with such critters. If the crazy dog is chewing on someone already it is gonna be a bloody mess all round for all involved pretty much. Ya have to wade in to the frey and get a clear cut or shot. That will almost always involve getting bit.......
Pit Bulls are some really strong pups.........I never want to piss one off or invade it’s arena.
An armed joovie or a gang, or a bad dog, or two, is a different matter. And here I am with just a revolver in my pocket...