The Trump administration has banned the high-power gun attachments of the type used in last year's Las Vegas shooting massacre of 58 people, giving the owners of "bump stocks" 90 days to turn in or destroy the devices and blocking owners from being able to register them.
United States President Donald Trump's Republican Party typically supports gun ownership, and its members have fiercely fought off perceived threats to the US constitution's second amendment guaranteeing Americans the right to bear arms.
His administration, though, is sidestepping any potential debate in Congress in issuing a final rule that adds bump stocks to a definition of machine guns written 80 years ago, during the heyday of gangsters' use of "tommy guns".
The attachments use a gun's recoil to bump its trigger, enabling a semiautomatic weapon to fire hundreds of rounds per minute, which can transform the firearm into a machine gun.
What is a bump stock?
A bump stock basically replaces a gun's shoulder rest with a "support step" that covers the trigger opening.By holding the pistol grip with one hand and pushing forward on the barrel with the other, the shooter's finger comes in contact with the trigger.
The recoil causes the gun to buck back and forth, "bumping" the trigger and firing rounds much faster than if the shooter were to manually pull the trigger each time.
The stock effectively turns a semi-automatic weapon into a fully automatic one that can unleash continuous rounds until the magazines are empty with a single trigger pull.
The Justice Department's regulation follows the lead of many states and retailers that imposed stricter limits on sales of guns and accessories after a deadly shooting at a Florida high school in February.
Gun Owners of America said that it was going to court to fight the new rule and would seek an injunction.
The group said the department was attempting to rewrite laws, the regulation would lead to bans on other weapons, and bump stocks did not qualify as machine guns.
On an earlier call with reporters, senior Justice Department officials said they were ready for any possible lawsuit and confident in the review of case law they conducted while writing and revising the regulation.
The department received nearly 190,000 comments on its proposal for the regulation.
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The websites for the most well-known bump stock manufacturers, Bumpfire System and Slide Fire, displayed notifications on Tuesday that they had already ceased direct sales of the devices.
RW Arms, which both manufacturers described as a leading retailer, was not immediately available to comment on the ban.
While bump stocks are not widespread, they are still plentiful in the market, with high sales over the internet and in big-box stores, the officials said on the call.
Walmart Inc stopped selling assault firearms and accessories in 2015.
After the February 14 shooting at Marjory Stoneman Douglas High School in Parkland, Florida, the retailer raised the minimum age for buying guns at its stores.
Other retailers, including Kroger Co, have also raised the minimum buying age.