Multiple news outlets have reported that the weapon used by Stephen Paddock in the Mandalay Bay shooting may have been a fully automatic weapon, or “machine gun.” The staggering number of casualties—58 dead and more than 500 sent to local hospitals at last count—and the rapid and continuous shots heard in footage posted to social media certainly seem to suggest this. If Paddock did, in fact, use a fully automatic weapon, Mandalay Bay will go down as one of the most unusual mass shootings in American history.
New, fully automatic weapons—weapons that reload automatically and fire continuously with one trigger pull—have been banned for civilians in the United States since the Firearm Owners’ Protection Act of 1986. Their use in crimes is incredibly rare, rarer even than the use of semi-automatic assault rifles like the AR-15 rifles used in the Sandy Hook and Aurora shootings or the Sig Sauer SIG MCX used in the Orlando shooting. Of the 91 American mass shootings catalogued by Mother Jones that have occurred since 1982, not one has seen the use of a fully automatic machine gun. It’s semi-automatic rifles—guns that reload automatically but fire only once per trigger pull—that have seen wide use in recent mass shootings and that probably constitute the majority of rifles used in homicides and other crimes. Still, rifles of all kinds constitute a small minority of criminally used guns: Only 2 percent of homicides were committed with rifles of any kind in 2014.
The illegal conversion of semi-automatic weapons to fully automatic weapons by criminals is occasionally a problem for law enforcement. In 1997, legally purchased and illegally converted rifles were used in a shootout following a bank robbery in the Los Angeles neighborhood of North Hollywood, during which the two perpetrators managed to outgun more than 300 officers. That incident led the Los Angeles Police Department and other departments around the country to arm themselves with more powerful weapons. A 1985 New York Times article details the woes of law enforcement officials dealing with widespread conversions of the Ingram MAC-10, popular among both far-right groups and gangs. “An ordinary citizen, with no felony convictions, can fill out a form, pay a $200 tax, and legally buy [an automatic] MAC-10 from a gun dealer,” it reads. “It is just as easy, however, for convicted felons, or others who do not want their names on a list, to buy a semiautomatic version of the gun and a couple of parts and put together an automatic MAC-10 with a silencer.”
New fully automatic weapons were banned completely for civilians—except manufacturers and gun dealers—the following year by an amendment to the Firearm Owners’ Protection Act, also known as McClure-Volkmer. That law didn’t solve the problem of semi-automatic conversions. And the bill as a whole contained pro-gun measures that won it support from the NRA, even though the organization denounced the automatic weapons amendment. In fact, then–NRA lobbying chief Wayne LaPierre was quoted in an article in the NRA newspaper Monitor as saying that repealing the automatic weapons ban would be “a top priority.” As detailed by the Violence Policy Center’s Josh Sugarmann in the Huffington Post in 2013, that article announced that an evidently short-lived organization, the National Firearms Association, had been created specifically to repeal the machine gun ban and to “educate the public about automatic firearms.”
Machine guns made prior to the cutoff date in 1986 remain legal but highly expensive—typically running in the five figures—and are tracked closely and individually by the Bureau of Alcohol, Tobacco, Firearms, and Explosives. According to the NRA, the state of Nevada, where the shooting occurred and where Paddock reportedly lived, does not impose any further restrictions on legally owned machine guns. There are reportedly around 193,000 pre-cutoff machine guns in legal ownership nationwide, and special events around the country offer gun enthusiasts space to celebrate and fire these weapons. In August 2016, the Atlantic’s John B. Fischer reported on the Oklahoma Full Auto Shoot. “For two days in June, hundreds of people traveled to Wyandotte, Oklahoma, for the opportunity to fire nearly every species of automatic weapon from the past century,” he wrote. “There were UZIs and M16s, Barrett .50-caliber rifles, WWII-era belt-fed Brownings, and even a Minigun—a giant, chair-mounted cylindrical device powered by a car battery.”
Gun owners who want weapons capable of fully automatic fire can’t legally modify the internal components of their semi-automatic rifles to accomplish this. But they can buy legal accessories like the Slide Fire or the GatCrank that help shooters mimic automatic fire without altering a semi-automatic gun’s internal mechanisms.