The added lethality of a bump stock is grotesque: The Las Vegas shooter appeared to fire as many as 90 bullets in 10 seconds. Without such a device, it would take several minutes to deliver that many rounds. You can find YouTube videos that show shooting experts testing bump stock devices, and even one of them sounded concerned about the availability of such firepower for as little as 99 bucks. "The packaging this thing came in said 'spray 600 rounds a minute,'" one expert says on his video. "That's right: 'Spray 600 rounds a minute.' They've since changed that on their website to say 'safe and precise,' but I think the people behind this could learn a couple lessons."