Bump stocks or bump fire stocks are gun stocks that can be used to help make a semi-automatic firearm fire more bullets and a faster speed.
In the United States, the legality of bump stocks have been in question since the 2017 Las Vegas shooting, in which 60 people were killed and 869 people injured. Several states passed legislation making it harder to own bump stocks following this shooting. In December 2018, the United States Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) published a rule that bump stocks were seen as "machine guns", and were effectively illegal under federal law. The U.S. Supreme Court ruled against this in June 2024 in Garland v. Cargill.
Bump stocks remain illegal in 15 states and the District of Columbia based on state bans not affected by the Supreme Court ruling.