hose who have handled a semiautomatic rifle of the sort used in the Marjory Stoneman Douglas shootings on Feb. 14 know that these are not ordinary weapons. Their power is unmistakable; an errant shot striking a small tree will go through that tree and the one behind that, and so on. A shot striking a human body will result in a cascading wave of force, crushing tissue and making recovery difficult for anyone who manages to survive the instant, massive bleeding or organ damage.