What is the Glock Switch Act?
On August 13, 2021, the ATF published a final rule, 2021R-08F, redefining “machinegun” to explicitly include standalone conversion devices like Glock switches. This administrative action, often called the “Glock Switch Act,” made possession of an unregistered auto sear a federal felony overnight, regardless of intent.
The Legal Shift: From Part to NFA Firearm
Prior to the 2021 rule, a Glock switch or auto sear was legally considered just a piece of metal—a component. Prosecution required proving intent to create an illegal machinegun. The new rule changed that fundamentally. Now, the device itself is legally classified as a “machinegun” under the National Firearms Act (NFA). This means that simply possessing a switch, a 3D printed file for one, or even certain pieces of billet aluminum that could be readily converted, constitutes possession of an unregistered NFA item. The penalty is up to 10 years in federal prison and a $250,000 fine per count. This isn’t a new law from Congress; it’s an ATF reinterpretation that closed what they saw as a loophole, impacting countless parts already in circulation.
Understanding the Device: Function Over Form
A Glock switch, correctly termed an auto sear or selector switch, is a small component that modifies the firearm’s fire control group. It typically replaces the rear slide cover plate. Its function is mechanical, not electronic. When installed in a Gen 1-4 Glock pistol (Gen 5 models have a modified ejector housing that often requires modification), the device interferes with the trigger bar’s reset. After the initial shot, the disconnector is prevented from re-engaging, causing the trigger to remain in the rearward position. As the slide cycles, it automatically trips the trigger, leading to continuous fire until the trigger is released or the magazine is empty. It’s a simple, purely mechanical alteration that radically changes the weapon’s function.
Legitimate Use and the NFA Process
It is a common misconception that these devices are universally illegal. They are not. They are strictly regulated under the NFA. Legitimate possession requires submitting ATF Form 1 (to “make” a machinegun) or Form 4 (to transfer one), paying a $200 tax, undergoing an extensive background check, and receiving approval from your local Chief Law Enforcement Officer (CLEO). This process can take 6-12 months. Once approved, the registered auto sear is serialized and its possession is legal at the federal level, though state laws may further prohibit them. This legal pathway is almost exclusively used by manufacturers, dealers, and specialized military/law enforcement entities. For the average citizen, navigating this process successfully for a post-1986 conversion device is virtually impossible due to the Hughes Amendment.
Consequences and Current Enforcement
The enforcement of this rule has been aggressive. The ATF and DOJ have prioritized cases involving switches, often stacking charges. For example, possession of a switch during another crime, like drug trafficking, triggers mandatory minimum sentences. Prosecutors are also targeting online vendors and social media sellers. It’s critical to understand that “constructive possession” applies. If you own a Glock and also possess a switch, even if they are not assembled, the ATF can argue you have possession of a machinegun. State and local police are now trained to identify these devices, and finding one during a routine traffic stop will lead to federal charges. This is the new reality post-2021 rule.
FAQ: Glock Switch Act
What is the Glock Switch Act?
The “Glock Switch Act” refers to the ATF’s 2021 final rule (2021R-08F) that redefined “machinegun” under federal law to include standalone conversion devices like auto sears. This administrative rule change made mere possession of an unregistered switch a felony, treating the part itself as a National Firearms Act firearm.
What does a Glock switch actually do?
A Glock switch is an auto sear that replaces the rear slide cover plate. It mechanically blocks the trigger bar reset, causing the pistol to fire continuously—one trigger pull results in multiple rounds—until the trigger is released or the magazine is empty. It converts a semi-automatic pistol into a fully automatic one.
Browse our glock switches collection
Last updated: March 27, 2026