Many of them would have been from full auto firearms, in which case it's darn good shooting. I've only fired a couple of magazines through an M-2 Carbine, but it was all I could do to put 2-3 rounds out of a short burst on a silhouette target at 15 yards.
I don't know (haven't seen) that any were from full autos. But in any case the perp was moving (from impacts if nothing else) and there was a lot of heavey brush that will deflect rounds. In any case not bad shooting.