Going to have to come down on the side of no charges filed and a despicable flyer on this particular case.
1) The dog should have been restrained, particularly if it was a barker.
2) It was 7am (as the flyer helpfully pointed out) and there were school children around a loose dog.
3) The shooter had the proper permit to carry concealed and used restraint and good target selection.
However, that being said, the fastest way to get a dog to act aggressively around you is to exhibit fear. Even a mild mannered dog will run and bark at a person they sense fears them. And even a trained attack dog will act warily around a person who they can sense no fear from. (They might still attack, but they are much more careful about the attack.)
I have run into around 5 people in my life that are deathly afraid of any and all dog. And guess what? Every dog barks at them when they first see them and growls with ears down even after they have been quieted by the owner.
This dog likely could have been told to go home in a firm voice and it would have left this gentleman alone. But the fact that it was loose in the first place puts the responsibility of this incident firmly on the dog's owner.
I'm sorry andyk I was responding to abathar( who had responded to your post ) and I got confused when I typed it in. I do apologize....