Julia Green 
Hunter“s Heart [PDF ebook] 

Simon, age 14, is obsessed with weaponry, survival tactics, and hunting. Against his mother“s wishes, he secretly orders a BB gun over the Internet and begins to practice with it. During a long, hot summer, he discovers a new obsession: Leah, the older girl next door. To her, he“s little more than a ‚project, ‚ but their relationship intensifies. Meanwhile, Simon“s mother has started a mortifying affair with his art teacher, Matt. When Simon realizes that Leah has begun modeling semi-nude for Matt, he snaps and makes use of his gun. The results are deadly, leaving Simon with a new understanding of himself and his capacity for violence.