First, the Times calls the AR-15 “the civilian version of the military’s M-16.” The M-16 is a machine gun, that throughout most of its history – and certainly in popular understanding – has been a fully-automatic weapon. When you squeeze the trigger on an automatic weapon, bullets keep firing out of it until you stop squeezing. The U.S. military has shied away from automatic firing, and the newest M-16s have other settings – three-shot burst (which, relative to the automatic setting, preserves ammo and inculcates more discipline among soldiers in combat) and semi-automatic.
AR-15s that are legal to buy do not have the three-shot burst that the military’s current M-16s have. They also don’t have the automatic-fire option that most people associate with the M-16.
If you’re going to use a famous gun as a point of reference, it seems responsible to mention that unlike the famous machine gun you’re comparing it to, the AR-15 is incapable of automatic or burst fire.