ar-15 lower

An AR-15–style rifle is a lightweight semi-automatic rifle based on or similar to the Colt AR-15 design. The Colt model removed the selective fire feature of its predecessor, the original ArmaLite AR-15, which is a scaled-down derivative of the AR-10 design (by Eugene Stoner). It is closely related to the military M16 rifle.
ArmaLite sold the patent and trademarks for both to Colt's Manufacturing Company in 1959 after the military rejected the design in favor of the M14. After most of the patents for the Colt AR-15 expired in 1977, many firearm manufacturers began to produce copies of the rifle under various names. While the patents are expired, Colt has retained the trademark to the AR-15 name and is the sole manufacturer able to label their firearms as such.
From 1994 to 2004, the Federal Assault Weapons Ban restricted the sale of the Colt AR-15 and some derivatives in the United States, although it did not affect rifles with fewer listed features. After the phrase "modern sporting rifles", to be used synonymously with the AR-15 style, was coined in 2009 by the US National Shooting Sports Foundation (NSSF), a firearms trade association, it was quickly adopted by much of the industry.
Beginning in the 2010s, AR-15–style rifles became one of the "most beloved and most vilified rifles" in the United States, according to The New York Times; the rifles have gained infamy due in part to their use in high-profile mass shootings. Promoted as "America's rifle" by the National Rifle Association of America, their popularity is partially attributable to active restrictions, or proposals to ban or restrict them. They are emblematic as being on the frontline of the debate over U.S. gun control.

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