Since 1989's Roger & Me, filmmaker/provocateur Michael Moore has assumed the David role in a multimedia battle against corporate Goliaths, using persistence and a bare-bones crew as his only weapons. His decidedly unsubtle mix of sledgehammer satire and populism can come off as strident, even for those who agree with his politics. In his television shows, films, and books, Moore gives an everyman spin to leftist ideology, but there's something condescending about his tendency to turn politics into a black-and-white morality play. His latest film, Bowling For Columbine, is a tonally and thematically scattershot but unforgettable examination of why the U.S. has a vastly higher rate of firearm-related homicides than other Western countries. Columbine begins as a savagely funny indictment of gun culture and the American fetish for violence, then dovetails into an examination of what one interviewee calls America's "culture of fear." In his attempt to discover the hidden cause of the nation's bloodlust, Moore interviews Marilyn Manson and South Park's Matt Stone, travels to Columbine, Canada, and his hometown of Flint, Michigan, and finally meets with NRA president and archetypal Stupid White Man Charlton Heston. At its worst, Columbine resorts to grandstanding and glib sarcasm, as in a sequence that sets a long list of U.S. foreign-policy initiatives to "What A Wonderful World." Moore's climactic meeting with a doddering Heston, meanwhile, would have seemed crass even if the director hadn't baited the fading icon with a picture of a murdered child. Getting Heston to come off as a xenophobic clod isn't exactly a Herculean accomplishment: Moore pretty much points him in the direction of a rope factory and lets the famous gun enthusiast to do the rest. Like much of Moore's work, Columbine mixes smart satire, petty bullying, and tough humanism. He isn't afraid to transcend the boundaries of good taste, and much of the film would come across as pat and mean-spirited if it weren't so clearly rooted in a sense of horror and concern. Throughout Columbine, Moore touches nerves, both in horrific footage of the Columbine shooting and in interviews where the subjects are so overcome with emotion that they lose their bearings. Bowling For Columbine is often uproariously funny, even though much of its queasy power comes from its acknowledgment that some matters are too horrifying to be washed away with cheap laughter, or packaged into soundbites.