Neighbor kid came over to my fence and lowered his pump bb gun at my dog, who was fenced in. He fired, I called police because he was a minor (nothing I could do) and his parents won't take care of it (this has gone on for a long time). In some cases, laws protect, even in the case of a bb gun. I have also had this kid taking target practice at my place and other homes in the area. Had his pellets whiz by my head on several occasions. What would you do? No fair assuming anything other than having Daytona cops, 'k?
I would call the police everytime I see the kid walking around with a bb gun. You have every reason to believe that he will continue to do mischief with it. He has demonstrated that he is irresponsible, and mean.
No state's laws allow anyone to fire a BB gun into your residential property, much less at you or your dog. Call the cops. Call and write the kid's parents explaining that if the kid ever so much as points his BB gun at your property again, you will sue them for damages for making it impossible to live safely at your own home, and for any medical or veterinary or property repair bills resulting from their delinquent son's shooting. And, if this is a smallish kid, look into your state's laws re citizen's arrests.