An AR-15 style rifle is a lightweight semi-automatic rifle based on the Colt AR-15 design. After Colt’s patents expired in 1977, an expanded marketplace emerged with many manufacturers producing their own version of the AR-15 design for commercial sale. They are referred to as modern sporting rifles by the National Shooting Sports Foundation, a firearms industry trade association, and by some manufacturers. Coverage of high-profile incidents where various versions of the rifle were involved often uses the shorthand AR-15.
AR-15 style rifles have become one of the “most beloved and most vilified rifles” in the United States, according to the New York Times. The rifle has been promoted as “America’s rifle” by the National Rifle Association. It has been used in many mass shootings in the United States. The Federal Assault Weapons Ban restricted the Colt AR-15 and derivatives from 1994-2004, although it did not affect rifles with fewer features. There are an estimated 10-12 million in circulation in the United States.