Gunman's rifle is civilian version of US military's M-16
WASHINGTON (AFP) - The weapon used in the Newtown school massacre is a civilian version of the powerful M-16 assault rifle issued to United States (US) troops since Vietnam, and can be purchased legally across the US.
Police said gunman Adam Lanza killed most of his victims with the Bushmaster AR-15, manufactured by Bushmaster Firearms International, which fires .223 calibre bullets, equivalent to North Atlantic Treaty Organisation's (Nato) standard 5.56mm ammunition.
Lighter than the rifles used in World War II or Korea, the round is designed to penetrate body armor or steel helmets and take out an enemy soldier from up to 600 meters, at a velocity of nearly 1,000m per second.
The AR-15 is also the template for the military's current M-4 rifle, a shortened carbine variant of the M-16, which is carried by the American soldiers in Afghanistan and around the world.