Call the cops.
What county do you live in?
I had a neighbor that thought it would be okay to do that with a .22, and he thought he would use my trailer as a backdrop, the bullet went through the door at head level, glad I wasn't in there. And I live in Portland. This was supposedly some big, badass, satanic, heavy metal guitar playing dude, who looked like he just shit his pants when the cops showed up. Oddly enough, two weeks later he moved.
Depending on where you live, you're dude is breaking several laws. He may also be a budding sociopath, with homicidal instincts. I'd be watching him very carefully, especially around kids and pets.
How old is this kid? Do his parents know that he's been doing this?
The police will DEFINITELY want to have a set down with him and his parents.
Good luck, stay tenacious until it's resolved! If he's not informed now of this unacceptable behavior, he'll likely progress into something even more, messy.
"Will you walk with me out on the wire, cuz baby I'm just a scared and lonely rider" - The Boss