In a wave of legislative changes across the United States, states like New Mexico and Alabama have taken steps to ban devices that modify pistols into machine guns. Despite their political differences, lawmakers in both Democrat-led New Mexico and Republican-led Alabama have enacted laws this year targeting these so-called Glock switches. This trend has now spread to at least half of the U.S. states, as these small but potent modifications have become more prevalent in law enforcement encounters over the last ten years.
Federal law has long prohibited machine guns and parts that transform semiautomatic weapons into automatic ones. Defined under U.S. law, a machine gun is capable of firing multiple shots with a single trigger pull, and this includes any components designed to turn a standard firearm into a machine gun. Generally, possession of machine guns manufactured after 1986 is illegal, with specific exceptions permitted for law enforcement, military, and authorized dealers. Nearly all conversion devices fall under this prohibition as they have been produced in more recent years. Being convicted of possessing such devices can lead to prison sentences of up to 10 years.
A Glock switch is a type of conversion device that can be affixed to a Glock pistol, a model popular among both law enforcement and criminals. These switches alter the internal trigger mechanism, resulting in continuous firing when the trigger is held down. Guns with these modifications can discharge dozens of rounds within seconds, resembling the firing capability of a standard machine gun. Beyond Glocks, other pistol brands and some semiautomatic rifles can also be adapted using these devices, often called auto sears, selector switches, or chips.
In recent years, the usage of auto sears has surged, partly due to the ability to produce them inexpensively with 3D-printing technology. Between 2012 and 2016, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) confiscated 814 machine gun conversion parts, a figure that ballooned to 5,454 from 2017 to 2021. Under the Biden administration, it was reported that approximately 12,360 suspected conversion devices were seized and reported to the ATF over a period ending in October 2024, with five states—Florida, Illinois, Texas, Montana, and North Dakota—accounting for nearly half of these seizures.
Alabama stands as the most recent state to legislate against Glock switches, with a new law making possession of such conversion parts a felony potentially punishable by up to 10 years’ imprisonment. This legislative move received bipartisan support in response to several fatal shootings believed to involve these devices, including a high-profile incident in Birmingham in September.
Similarly, New Mexico implemented a law in February that established possession of a conversion device as a felony with penalties extending up to three years in prison. New Jersey is also moving forward with similar legislation, and governors in states like Virginia have signed laws against the possession of auto sears. However, recent proposals to broaden existing bans have faced vetoes.
Gun control advocates, represented by groups like Everytown for Gun Safety, see state laws as a potentially more straightforward alternative to federal prosecution. They are supporting additional legislation in states such as California, Maryland, and New York that would criminalize the sale of pistols easily converted into machine guns. Nick Suplina, a senior executive at Everytown, stresses the importance of holding manufacturers accountable for producing firearms that can be readily adapted into automatic weapons.
In response, gun-rights organizations such as the National Rifle Association argue that federal prosecutors already have the necessary tools to handle gun conversion violations, suggesting state laws are redundant. Gun Owners of America, another prominent advocacy group, argue that possession of machine guns is a Second Amendment right. Federal Affairs Director Aidan Johnston of Gun Owners of America views state laws against conversion devices as redundant, asserting they serve primarily as political posturing. He notes that firearms converted to automatic functioning can be practical for tasks like managing overpopulation of feral hogs, challenging the assumption that possession of such modified firearms indicates criminal intent or violent tendencies.