What to know about bump stocks and the Supreme Court ruling striking down a ban on the gun accessory

abcnews.go.com:

The gun accessory the Supreme Court just ruled on allows a rifle to fire dozens of bullets within seconds

WASHINGTON — The U.S. Supreme Court has struck down a ban on bump stocks, the gun accessory used in the deadliest shooting in modern American history — a Las Vegas massacre that killed 60 people and injured hundreds more.

The court's conservative majority said Friday that then-President Donald Trump's administration overstepped its authority with the 2019 ban on the firearm attachment, which allows semiautomatic weapons to fire like machine guns.

Here's what to know about the case:

Bump stocks are accessories that replace a rifle's stock, the part that gets pressed against the shooter's shoulder. When a person fires a semiautomatic weapon fitted with a bump stock, it uses the gun's recoil energy to rapidly and repeatedly bump the trigger against the shooter's finger.

That allows the weapon to fire dozens of bullets in a matter of seconds.

Bump stocks were invented in the early 2000s after the expiration of a 1994 ban targeting assault weapons. The federal government approved the sale of bump stocks in 2010 after the Bureau of Alcohol, Tobacco, Firearms and Explosives concluded that guns equipped with the devices should not be considered illegal machine guns under federal law.

According to court documents, more than 520,000 bump stocks were in circulation by the time the government reversed course and imposed a ban that took effect in 2019.

More than 22,000 people were attending a country music festival in Las Vegas on Oct. 1, 2017, when a man opened fire on the crowd from the window of his high-rise hotel room. He fired more than 1,000 rounds in the crowd in 11 minutes, leaving 60 people dead and injuring hundreds