Congressional Democrats have reintroduced legislation to focus federal efforts on reducing the proliferation of illegal machine gun conversion devices, also known as auto sears.

The Preventing Illegal Weapons Trafficking Act of 2023 would direct the Department of Justice, Department of Homeland Security, and the Department of the Treasury to develop “a coordinated national strategy” to prevent the importation and trafficking of auto sears. It would also instruct the attorney general to collect data on the recovery of the devices in crimes and include it in an annual firearms trafficking report.

The legislation is a response to a March 2022 investigation by The Trace and VICE News that found that auto sears were involved in dozens of shootings carried out by extremists, mass shooters, and drug traffickers. Our reporting showed that more than a thousand illegal auto sears had been recovered in connection with at least 260 federal prosecutions since 2017, with the number of cases filed annually climbing nearly 800 percent in five years.

The Democrats’ bill was introduced in the House by Representative Abigail Spanberger of Virginia and Representative Sean Casten of Illinois. Senators Amy Klobuchar of Minnesota and Gary Peters of Michigan introduced companion legislation in the Senate. 

“Law enforcement must do more to protect our communities from gun violence by stopping the flow of illegal gun modification devices into and throughout our country,” Peters said in a news release. “This bill will enhance coordination across law enforcement agencies to prevent these dangerous and deadly devices from being used.”

Machine guns are among the most regulated firearms in the United States, but auto sears provide a quick and inexpensive workaround. The small conversion devices can transform a semiautomatic gun into a weapon capable of emptying an entire magazine with a single pull of the trigger. They require little technical knowledge to use and can cost as little as $20. 

The Trace and VICE News’ investigation found that many auto sears recovered in the U.S. were supplied by companies in China, where manufacturers list the devices on online marketplaces and sell directly to consumers. Auto sears can also be made at home using a 3D printer. 

The bill seeks to hold companies that facilitate the trafficking of auto sears accountable, by requiring that proceeds from trafficking machine gun conversion devices are subject to forfeiture. 

The legislation is the latest in a series of efforts from lawmakers urging federal law enforcement to take action on auto sears. In April 2022, after a gunman armed with a converted Glock handgun opened fire in Sacramento leaving six dead and 12 wounded, a group of more than 40 members of Congress signed a letter urging the Bureau of Alcohol, Tobacco, Firearms and Explosives to be more explicit about the illegality of the devices.

In February, Steve Dettelbach, the first confirmed director of the ATF in nearly a decade, said the agency was prioritizing the recovery of auto sears. “This is a problem that needs to be focused on immediately,” he said. “These devices are flooding our communities.”