Some states and cities are taking the lead on banning bump stocks as efforts stall in Washington, D.C.
The controversial device was used in the Las Vegas shooting, allowing a semi-automatic rifle to mimic a fully automatic firearm.
Massachusetts and New Jersey as well as the cities of Denver and Columbia, South Carolina, have enacted laws prohibiting the sale and possession of the devices. A little over a dozen other states are also considering bans.
Gun-control advocates say the push fits a pattern in gun politics: inaction in Washington that forces states to take charge. Gun-rights advocates call it a knee-jerk reaction that will do little to stop bad guys from killing, and they're vowing a legal challenge.