Marching around the stage in a theater in Lakeport, California, Lt. Colonel Dave Grossman tells his audience that they shouldn’t go out looking for people to kill, because those who need killing—the “gangbangers,” terrorists, and mass murderers—will come to them. All they need to do is be ready. “Are you prepared to kill somebody?” he asks me and the small group of “armed citizens” who’ve paid $90 or more to see him. “If you cannot answer that question, you should not be carrying a gun.”