WASHINGTON — Firearm bump stocks would have to be surrendered, destroyed or made inoperable under a ban proposed Friday by the Justice Department. The devices, which allow semi-automatic weapons to fire as fast as a machine gun, became the focus of concern following the discovery that Stephen Paddock attached them to 14 of the 22 rifles he used in the October 2017 shooting rampage in Las Vegas, killing 58 people and injuring more than 700. "After the senseless shooting in Las Vegas, this proposed rule is a critical step in our effort to reduce the threat of gun violence that...