Sig Sauer MCX vs AR-15

From the article:

AR-15s that fire only on semiautomatic are generally legal in the United States, and are widely owned by assault-rifle enthusiasts. They are also sometimes used in crimes, and have been involved in some of the most deadly mass shootings in American history, including the massacre in December in San Bernardino, Calif., which killed 14 people, and the attack in 2012 at Sandy Hook Elementary School in Newtown, Conn., which killed 26 people, 20 of them children. (That gunman also killed his mother at home before driving to the school.)