The trend is certainly interesting and a bit surprising. As we have seen according to the stats felons with (hand)guns are responsible for a high percentage of the gun violence, especially murders in big cities. So a seemingly relative simple tool in the fight against it would be a strict enforcement of the laws concerning felons and their most dangerous tools.

BTW: As I understood Mr.Bratton he was talking that in the case of a deranged killer no bullets in a clip would be the best option as it makes it more cumbersome to kill many persons. I can fully agree with that scenario.