Actor Ben Barnes, best known as Prince Caspian in “The Chronicles of Narnia” films, is on the cover of Fault magazine to promote “God Only Knows,” the gangster film he shot around Boston and Rhode Island last winter with Stoughton actor-dancer Kenny Wormald , Harvey Keitel, and Leighton Meester. Barnes, who shot the thriller “Locked In” in Boston in 2009, said of his latest project, “This was maybe my favorite role I’ve played. I have rarely been afforded the opportunity to play the tough guy so it was very rewarding. I watched a lot of Pacino movies and [gangster] movies during shooting and watched actors who are effortlessly tough like Tom Hardy. It helped that most of the other character were played by real-life Boston tough guys, rappers, footballers, ex-cons, etc.” By rappers, we assume Barnes is referring to his costar Slaine, the Boston lyricist/actor who appeared in “Killing Them Softly” with Brad Pitt and “The Town” with Ben Affleck. As for the ex-cons, well, we just can’t say who Barnes is talking about.