Auto Sear 101
Everything you need to know about the gun conversion device showing up in criminal investigations across the U.S.
By: Allison Jordan
Despite being around since the 1970’s, demand for the auto sear, also known as a “switch” or “chip,” has recently exploded in popularity on the black market, becoming a favorite among criminal and anti-government extremist circles.
These illegal devices are detrimental to community safety and have been tied to shootings by extremists, mass shooters, and drug traffickers. By turning firearms into functional machine guns, these conversion devices make incidents of gunfire even more deadly.
As local, state, and federal law enforcement agencies continue reporting an alarming increase in the number of auto-sear devices recovered during criminal investigations, demands for action to address auto sear proliferation have grown.
In 2022, an armed gunman used a converted Glock handgun to open fire on a crowd in Sacramento, CA, leaving six dead and 12 wounded in a violent mass shooting. After, more than 40 members of Congress signed a letter demanding the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) release explicit guidance on the illegality of these devices. More recently, ATF Director Steve Dettelbach publicly called for immediate action to address the surge in crimes involving auto sears.
To help break down the basics, this guide covers everything you need to know about auto sears.
What exactly is an auto sear?
An auto sear – colloquially known as an “auto sear” when installed in semi-automatic weapons and a “switch” when installed in Glock-style pistols – is the most common machine gun conversion device.
These devices are cheap to purchase, difficult for law enforcement to detect, and can be installed with little to no experience required. These small metal or plastic conversion devices can be installed on most semi-automatic firearms, effectively transforming a legal weapon into a machine gun.
Auto sears can be purchased online or created using 3D printers, enabling individuals to easily and affordably equip their weapons with automatic capabilities, allowing the firearm to discharge an entire magazine with a single trigger pull. While auto sears can be installed in various types of rifles or handguns, they are particularly common for Glock pistols due to the firearm's internal design which facilitates easy modification.
How does a machine gun conversion device work?
Semi-automatic firearms feature a backplate and a sear mechanism inside the gun, which prevents the firearm from firing more than one round at a time. An auto-sear can be installed within the trigger mechanism to override the trigger bar. This, in turn, disables the sear from engaging, allowing the shooter to continue firing bullets until the trigger is released or ammunition is depleted.
When retrofitted with a switch, semi-automatic handguns and rifles can discharge up to 1,200 bullets per minute or 20 rounds per second. Concerningly, these devices are extremely easy to install with instructions for attaching switches to a handgun found easily online.
Are auto sears legal?
No.
The ATF classifies auto sears as machine guns, making it a federal offense to possess an auto sear.
In 1981, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) classified auto sears as machine guns, subjecting them to regulation under the National Firearms Act. This ruling established that the possession of an auto sear was, in legal terms, equivalent to owning a machine gun, regardless of if the device was installed on a firearm.
Today, owning or possessing an auto sear without the appropriate licensing is punishable with up to 10 years in prison. However, despite illegality, auto sears have continued to flood illicit markets.
ATF data from 2017 to 2021 revealed a 570 percent increase in recoveries of auto sears and machine gun conversion devices during criminal investigations compared to the previous five-year period.
If these devices are illegal, how are people getting access to auto sears?
While previously difficult to obtain in the United States, auto sears have become increasingly easy to acquire due to 3D printers, online platforms, and international markets.
Today, auto sears are often 3D printed using switch design files sourced through the 3D gun building community or sold online on popular social media platforms, sites, and forums for as little as $20, with some of the most popular sites being Alibaba, AliExpress, Wish, eBay, Amazon, Instagram, and more. Once sold, these devices are then shipped using false documentation and packaging labels.
Additionally, auto sears and other conversion devices are frequently sold and imported by foreign manufacturers, particularly those based in China, under the guise of innocuous everyday items such as paperweights, wall fixtures, or coat hangers. In fact, the United States has become such a popular hub for auto sear smugglers operating out of China that Homeland Security Investigations established a task force with Customs and Border Protection, ATF, USPS, and Chinese counter-smuggling officials to address the flow of these items.
After arriving in the United States these devices often enter underground criminal markets and are funneled to street gangs and cartels, anti-government extremist groups, and other dangerous individuals. This problem is likely growing as auto sears are becoming more economical to make and easier to obtain.
Are auto sears used in violent crime?
Yes.
Auto sears are increasingly being used in shootings and violent crime across the country:
In 2019, members of the Mongolian Boys Society, a criminal street gang, killed four and wound six more at a family gathering in Fresno, CA, using an automatically converted Glock in what they allege was a retaliatory attack against the Asian Crips gang.
In 2021, members of the “Boogalo Bois,” an anti-government accelerationist group that believes in a second-coming U.S. civil war, used weapons converted with auto sears to attack a federal courthouse.
In September, 2022, a Houston man armed with a converted Glock pistol opened fire on police officers after they attempted to arrest the assailant on a narcotics warrant, killing one officer and wounding another.
In April, 2022, a gunman armed with a converted Glock handgun opened fire in downtown Sacramento leaving six dead and 12 wounded in a deadly massacre.
In May, 2022, a sniper using weapons retrofitted with conversion devices shot more than 200 rounds of ammunition at the Edmund Burke school from a nearby apartment complex window Northwest Washington, D.C.
An investigation by the Trace and Vice news found more than a thousand illegal auto series have been recovered in connection with at least 260 federal cases filed in the last five years, with switches used in shootings by mass shooters, drug traffickers, and anti-government extremists.
Law enforcement and public safety officials around the country are sounding the alarm about the dramatic increase in the recovery of auto sears and other machine gun conversion devices at crime scenes in their communities. And in 2021, the ATF reported seizing 1,500 weapons modified with auto sears – a 400 percent increase from 2020 which saw only 300 converted firearms recovered. Several law enforcement agencies have reported similar increases in auto sear recoveries.
In 2022, Chicago police seized over 350 auto sear-equipped handguns, a drastic increase from 2018 which had no auto-sears recovered at crime scenes.
Over 775 Glock switches were recovered by Dallas police in 2022.
During the first half of 2021 alone, D.C. police recovered more than double the number of auto sears recovered over the same period in 2020.
What is the solution for addressing auto sears?
Currently, there are two main avenues for addressing the proliferation of auto sears. The first through legislative change, and the second through administrative actions.
To enact change at the federal level, Democratic lawmakers recently introduced the Preventing Illegal Weapons Trafficking Act of 2023. If passed, this law would direct designated federal agencies to develop a coordinated national strategy to prevent the importation and trafficking of auto sears, in addition to instructing the U.S. attorney general to collect recovery data on machine gun conversion devices in crimes and include this information in annual firearm trafficking reports. The bill also proposes accountability measures for companies that facilitate the trafficking of auto sears, stating that proceeds collected from these devices are subject to forfeiture.
Some states have enacted their own laws to address this issue. For example, Indiana recently passed legislation to criminalize possession of auto sears under state law, regardless of if the device is attached to a firearm.
The proliferation of auto sears can also be addressed administratively. Several solutions to address this crisis can be found in the National Firearms Commerce and Trafficking Assessment, an expansive federal report released by the ATF. Agency recommendations include expanding training to federal, international, state, local, and tribal law enforcement agencies on how to identify, intercept, and submit tracing requests on auto sears, and strengthening ATF trace capabilities for tracking conversion devices. The report also recommends entering into an intelligence partnership with U.S. Customs and Borders Patrol for illegal imports.
Other advocates suggest the ATF should take regulatory action against gunmakers to force companies that manufacture the firearms that can be easily converted to change their designs or face stricter classifications.
While infrequently used, the ATF has flexed its regulatory powers in the past to prevent automatic conversations of firearms. In 2021, the ATF required a Tampa based boutique gunmaker to offer an exchange program for customers who purchased the semiautomatic T36 rifle, a firearm designed and sold by the gunmaker, after agents were able to install fully automatic parts in the gun’s receiver. As part of the mandate, the dealer was required to provide a roughly $200 upgrade for each customer and agree to build all future guns to be less capable of accepting fully automatic parts.
Allison Jordan is Research Associate, Gun Violence Prevention at Center for American Progress
Gif image courtesy of The Trace