The AR-15 used in Florida school attack is a fearsome weapon designed for maximum damage
A so-called militiaman standing in a field with an assault rifle. (Shutterstock)

AR-15, used in Florida school attack, is a fearsome weapon designed for maximum damage

The AR-15, the semiautomatic rifle used in Parkland, Fla., in the deadliest high school shooting in U.S. history, uses bullets that can cause softball-size exit wounds, leaving behind a significantly larger trail of mangled tissue compared with handgun bullets.