I believe they say he fired the weapon on several occasions.
Also, on the older M-16's (there is a 3-round burst and single shot), I don't know the age of his weapon, but it seems funny that they describe "multiple rounds firing with a single pull of the trigger" and don't quantify it.
"No matter how one approaches the figures, one is forced to the rather startling conclusion that the use of firearms in crime was very much less when there were no controls of any sort and when anyone, convicted criminal or lunatic, could buy any type of firearm without restriction. Half a century of strict controls on pistols has ended, perversely, with a far greater use of this weapon in crime than ever before."
-- Colin Greenwood