Bump stocks, which allow rifles to mimic automatic weapons, are now illegal to own, buy or sell

Owning, buying, selling, or otherwise transferring a bump stock, a device that allows rifles to mimic automatic weapons, becomes illegal Tuesday, when a federal ban goes into effect. 

An October 2017 mass shooting in Las Vegas that killed 58 prompted action on bump stocks by President Donald Trump. In February 2018, Trump instructed the attorney general to regulate their use and in December, Justice Department officials issued the ban, giving owners 90 days to either turn bump stocks over to federal agents or melt, shred or crush them. 

Bump stocks combine two legal devices, a plastic stock and a firearm, that together function like a machine gun. The bump stock harnesses the recoil of the rifle to accelerate trigger pulls, technically “bumping” the trigger for each shot after it bounces off the shooter’s shoulder.

In February, a U.S. District judge in Washington rejected challenges to the ban.

Judge Dabney Friedrich rejected arguments that the rule was rushed through the administrative process, or that it was improperly issued by then acting Attorney General Matthew Whitaker. She wrote that the Bureau of Alcohol, Tobacco, Firearms and Explosives was within its right to redefine ambiguous terms that the government had previously concluded constrained them to allow the devices