“Hired Gun” (*** out of four) was an affecting documentary about the life of session musicians for such superstars as Kiss, Alice Cooper, Metallica, and many others from their highpoints to being on stage with the bands they love to the lows of often being unceremoniously dumped and often never receiving proper credit for what they’ve contributed personally and musically. Features numerous interesting interviews with Eric Singer, Jason Newsted, Alice Cooper, and (especially) Liberty Devvito and some rare and explosive concert footage. Film particularly paints an unflattering portrait of Billy Joel.