"Shooting: Movie theater in Aurora, Colorado Date: July 20, 2012 Perpetrator: James E. Holmes Guns: Holmes used a semiautomatic Smith & Wesson M&P15 (a variation on the military’s M16 weapons), a 12-gauge Remington 870 shotgun, and a semiautomatic .40-caliber Glock 22, killing 12 and injuring 70. The New York Times reports that these three guns are some of the most popular in the U.S.—so widely used, in fact, that a “three-gun competition” has been established to test gun enthusiasts’ proficiency on each in a target-shooting game of speed. How he got them: All three guns were purchased legally in 2012 between May 22 and July 6 at three different Colorado gun stores."