Well I suppose there is a chance but I have shot pits that were comin right at me. If you stay calm, their gonna get there soon enough, and you just wait until there right there, and do'em. I was a tactical K-9 Sgt. trainer for a number of years, so I have been bit by some pretty nice dogs. Pit's are determined but not smart. You can stick the muzzle to him if you have to. A pistol in close is good for dogs that don't run, or come in after you, if your geared that way yourself.
As far as considerate goes, it's the owners fault, but the dog is the problem. There's no reason to take it outside my property, and I try never to carry the problem any further than it has to go, so takin it into their home (pepper spray on the dog) is not on my agenda. I didn't want the problem in the first place, but I will make my point in such a way it isn't likely anyone will want to continue.
As far as your question on ammo, my reply is that a 125 grain jacketed HP out of a 357 mag, works just as good on pit bulls as it does two legged gremlins, and I have used it on a number of pits.