Shooting a dog is a big responsibility. Almost like shooting a person.

My neighbor's dog poops and digs in my yard. It growls at me, but it's a wiener dog. If it came at me I would boot it into tomorrow. I thought about shooting it with a paint ball gun so it could go home with a splotch.
It's owner is a teacher who should know better. People should know better, but they don't.

I'm a bicyclist. We used to like in a rural area where people let their dogs run free - against the law. I used Halt on them. It is what the mailman uses. The trick with Halt is to let the dog get real close then give them a good dose right in the kisser. You have to hold off shooting until "you can see the whites of their eyes." Wait until they are almost in contact distance. I've actually used it a good number of times and I can testify to it's effectiveness.