“Bang Bang” (*1/2 out of four) was a gritty but grimy underworld melodrama about a long-retired boxer (Tim Blake Nelson) obsessed with rectifying the sins of the past and enacting revenge on the boxer (Glenn Plummer) who defeated him and ended his career. Inspirational melodrama has little inspiration or emotional resonance since Nelson’s character (and performance) is unlikeable and thus film wallows in unpleasantness and never delivers the knockout punch it wants. Plummer is wasted in key supporting role; his role in “South Central” was similar to Nelson’s but carried much more bang and passion.