Newtown Massacre: What Is a Bushmaster .223?

Law enforcement officials said that Adam Lanza was armed with four firearms when he started his rampage at a Connecticut elementary school Friday that ended in the deaths of 20 children and seven adults, but nearly all the killing was done with just one of the guns: a .223 caliber Bushmaster semiautomatic rifle. Lanza used the rifle, a modified civilian version of the military's M-16 similar to the popular AR-15, as he stalked through the school and opened fire on children as young as five. Dr....Full Story