Bushmaster XM-15

The Bushmaster XM-15 series (or XM15) is a line of AR-15 style semi-automatic rifles, and carbines, manufactured by Bushmaster Firearms International. Variants include the Bushmaster M4-type Carbine, Patrolman series, QRC series, Bushmaster XM15-E2S and the Carbon 15 line.
Variants.
The standard XM-15 has a forged 7075T6 aircraft-grade aluminum upper and lower receiver. Barrels of XM-15 firearms have a heavy profile and are hard chrome-lined 4150 alloy steel or 416 stainless steel. In Bushmaster's 2016 sales brochure, all new-production XM-15s are stated to be supplied with a 4150 steel barrel. The standard barrel has rifling of 1 turn in 9".
Notoriety.
According to Gregg Lee Carter, an American sociologist who studies gun violence in the United States, the firearm was designed to comply with the 1994 Federal Assault Weapons Ban. The Bushmaster XM15-E2S "M4 type" carbine gained notoriety for its use in the October 2002 Beltway sniper attacks. 
A Bushmaster XM-15 was used in the December 2012 Sandy Hook Elementary School shooting. Just before the two-year anniversary of the massacre, nine families of the 26 victims of the shooting filed a class action lawsuit in Connecticut against Bushmaster, Remington Arms and others, seeking "unspecified" damages for the defendants' purported negligent entrustment and illegal marketing of the XM-15 rifle. Plaintiffs argued that both theories of liability fell within exceptions to the 2005 Protection of Lawful Commerce in Arms Act, which affords broad civil immunity to gun manufacturers. The case was dismissed in superior court and was appealed to the Connecticut Supreme Court. In March 2019, the Connecticut Supreme Court reinstated the wrongful death lawsuit, holding that the plaintiffs successfully pleaded a cause of action for illegal marketing. Remington appealed to the United States Supreme Court, which denied review on November 12, 2019. The trial is scheduled for September 2021.
An XM-15 was also used in the 1997 North Hollywood shootout.
An XM-15 was also used in the 2018 Nashville Waffle House shooting.
An XM15-E2 was captured from Islamic State fighters in Sinjar Mountains by Peshmerga during the Iraqi Civil War.
Legality.
As of October 2nd, 2000, California has banned the Bushmaster XM15 by name in the Kasler v. Lockyer Assault Weapon List, among other AR-style rifles by Armalite, DPMS, Colt, and Eagle Arms, to name a few. 
As a result of the Sandy Hook school shooting: 