A Texas man is the first person to be charged under a federal ban on bump stocks, devices that allow a semi-automatic firearm to fire rapidly like a machine gun, the Justice Department said Thursday. Ajay Dhingra, 43, of Houston, came on the radar of the U.S. Secret Service in August after he sent an email to the George W. Bush Foundation asking the former president to "send one of your boys to come and murder me," according to court records. Prosecutors allege that Dhingra had previously been involuntarily committed to a psychiatric facility and was prohibited from owning firearms....