ORLANDO, FLORIDA — On June 12, Omar Mateen committed the worst single-day mass shooting in U.S. history, using the same type of gun that has killed countless innocents in similar tragedies. <br /> <br />According to the National Rifle Association, the AR-15 is America’s most popular rifle, with at least 9 million in circulation as of 2014, reports USA Today. <br /> <br />The AR-15 was created by ArmaLite in 1957 for the U.S. Army, which needed a lightweight, high-velocity rifle. The original prototype didn’t pass standards, but a redesigned version was adopted by the military in the 1960s and renamed the M16. The AR-15 we know today is its civilian equivalent. <br /> <br />The fully automatic M16 can fire 30 rounds in two seconds with one pull of the trigger. The AR-15 and similar style rifles are 22-caliber semi-automatic weapons that require the trigger to be pulled and released for every shot fired. <br /> <br />The rifle has been used in at least five mass shooting incidents since 2012. Most recently, Mateen used it to open fire at a gay nightclub in Orlando. <br /> <br />In states like Florida, no gun license is required to buy a gun. The Florida state legislature mandates a three-day waiting period for small guns between purchase and delivery, but not for rifles and similar guns.
