The Trump administration has concluded that bump stock devices, and those that are similar, mimic "machine guns" and are therefore illegal. The rule takes effect in 90 days, barring legal action.
MARY LOUISE KELLY, HOST: To another story now - the Trump administration is following through with a promised ban on bump stocks. President Trump about this earlier today.</s>PRESIDENT DONALD TRUMP: This morning, we also completed the process to issue a new regulation banning bump stocks.</s>MARY LOUISE KELLY, HOST: Bump stocks are the aftermarket gun attachments that let semiautomatic rifles fire much more quickly. They effectively turn rifles into machine guns. The ban gives people 90 days either to destroy their bump stocks or turn them in. NPR's Martin Kaste reports on how this change came about. And a warning - this story contains the sound of gunfire.</s>MARTIN KASTE, BYLINE: Before October of last year, most people had no idea what a bump stock was. Then came the mass shooting in Las Vegas - 58 people killed, hundreds injured, the gunman shooting down into a crowd from his hotel room, shooting with what sounded like a machine gun.</s>MARTIN KASTE, BYLINE: Police on the scene assumed it was a machine gun. Only later, when the shooter was dead, did they find his semiautomatic rifles had been outfitted with bump stocks.</s>MARTIN KASTE, BYLINE: The thing about stocks and similar devices is that they're basically a novelty. Before Las Vegas, they'd almost never been used in a crime. This is a YouTube video of a gun enthusiast in Louisiana, Jeff LaCroix, showing his daughter how to shoot one.</s>MARTIN KASTE, BYLINE: (SOUNDBITE OF YOUTUBE VIDEO, "HALEY BUMP FIRING WITH THE STOCK BEFORE THEY TAKE THEM AWAY"</s>JEFF LACROIX: Hold tight right there. OK. Push - more pressure. Hold...</s>JEFF LACROIX: Oh, my God.</s>JEFF LACROIX: (Laughter).</s>JEFF LACROIX: OK. All right.</s>JEFF LACROIX: (Laughter).</s>MARTIN KASTE, BYLINE: And even LaCroix sees the bump stocks as a rare indulgence. As he says in the video, they're almost too expensive to shoot.</s>MARTIN KASTE, BYLINE: (SOUNDBITE OF YOUTUBE VIDEO, "HALEY BUMP FIRING WITH THE STOCK BEFORE THEY TAKE THEM AWAY"</s>JEFF LACROIX: We don't shoot this thing much. And I hadn't let you shoot it before is because it costs too much money damn to feed it. You can point $50 worth of rounds down range in about five seconds if you want to - or less than that.</s>MARTIN KASTE, BYLINE: Bump stocks also make your rifle jump around a lot, making it very inaccurate. And that's because of how they work. The attachment simply harnesses the recoil energy from the gunshot before to pull the trigger again for you, faster than you could do with your finger. It's never been considered a reliable way to fire a rifle. And the attachments have been sold mainly by small aftermarket vendors.</s>LAWRENCE KEANE: Most people in the industry didn't know what they were.</s>MARTIN KASTE, BYLINE: That's Lawrence Keane with the industry trade group National Shooting Sports Foundation, commenting last week on this impending ban.</s>LAWRENCE KEANE: It's not something we're concerned about. In particular, we didn't really comment on it. It is such a small, small niche. It's really quite inconsequential to the overall scheme of things for the industry.</s>MARTIN KASTE, BYLINE: While the mainstream gun industry has kept its distance from bump stocks, some gun rights activists have rallied to the cause. They worry about a slippery-slope effect. With the spread of 3D printers, it's now easier for people to make their own homemade attachments. And some of the activists worry that the government might eventually just broaden this ban to include any rifle that could be bump fired. The NRA expressed its disappointment that owners of bump stocks will have to turn them in or destroy them. They have 90 days to do so, and there's no amnesty here for people who bought them when they were still allowed by federal regulators. Another group, Gun Owners of America, promised to sue to block the rule from taking effect.</s>MARTIN KASTE, BYLINE: Martin Kaste, NPR News.