Bump stocks — the attachment used by the killer during the 2017 Las Vegas massacre to make his weapons fire rapidly like machine guns — will become illegal in the U.S. next week.

It's the only major gun restriction imposed by the federal government in the past few years.

Owners of the devices are anxiously watching the legal wrangling and wondering what to do. Their options are to destroy the devices, turn them over to federal authorities or risk getting caught and face a felony.

Federal authorities have estimated there may be as many as 500,000 in circulation.