Regulators have flip-flopped on legality of some bump stocks

Bump stocks like the ones found in the hotel room of the Las Vegas shooter have been around for two decades, but federal regulators have flip-flopped about whether some versions are legal.

Bill Akins was the first person to file a patent for an attachment to a rifle stock that allows the recoil to rapidly depress the trigger and shoot faster.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives initially let Akins sell his device. Then it ruled that the attachment illegally converted regular guns to machine-guns.

The agency has found that current bump stocks on the market only speed the triggering of a gun rather than convert it to shoot multiple bullets per pull — and therefore are legal.

The National Rifle Association gas called for the ATF to review whether bump stocks comply with federal laws.

Gun control advocates, Democrats and some Republican members of Congress have called for a law to ban them.