What Are Glock Switches?

You've seen the videos: a Glock pistol firing at a cyclic rate that sounds more like a submachine gun. That's not a modified firearm—it's a standard Glock equipped with a small, aftermarket component called a switch. Also known as auto sears or selector switches, these devices mechanically convert a semi-automatic Glock pistol into a fully automatic machine pistol. The most common is the "Glock 18 switch," designed to mimic the function of the factory full-auto Glock 18's selector lever.

The Mechanics: How a Glock Switch Works

A Glock switch is a drop-in auto sear. It replaces the rear cover plate on your Glock's slide. Inside is a spring-loaded lever or pin. When installed, this component engages the pistol's trigger bar and firing pin safety in a specific sequence. As the slide reciprocates after a shot, the switch automatically resets the trigger mechanism, allowing it to fire again the instant the slide returns to battery. This bypasses the need for the shooter to release and pull the trigger for each round. The result is uncontrolled, fully automatic fire until the magazine is empty. It's a purely mechanical modification; no electrical components are involved. The installation requires minimal tools, but the function radically alters the firearm's behavior and legal status.

Common Models and Compatibility

Not all switches are created equal. The most ubiquitous design is the "Glock 18 style" switch, a small rectangular unit with a selector lever that toggles between semi and auto. These are typically made from CNC-machined aluminum or steel. They are model-specific. A switch for a Glock 17/19 Gen 3 will not fit a Gen 5 model without modification due to differences in rear slide profile and pin placement. Switches for subcompact models like the Glock 26 or larger frames like the Glock 34 also exist. At Theglockswitchshop, we categorize our inventory by exact generation and model to ensure compatibility. It's critical to match the switch to your specific pistol; a misfit part won't function and can cause dangerous malfunctions.

The Legal Reality: NFA and the "Machinegun" Definition

This is the most critical section. Under the National Firearms Act (NFA) of 1934 and the subsequent Hughes Amendment of the Firearm Owners' Protection Act (FOPA) of 1986, a "machinegun" is defined as any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot by a single function of the trigger. This definition includes the firearm itself and any part or combination of parts designed and intended solely for use in converting a weapon into a machinegun. A Glock switch meets this definition. Possession or installation of one on a semi-automatic Glock, without the proper federal licensing and tax stamp, is a felony punishable by up to 10 years in prison and significant fines. This is federal law, applicable in all 50 states.

Function vs. Fantasy: Practical Implications

Beyond legality, using a switch has severe practical downsides. A Glock 19 with a 15-round magazine will empty in less than one second. Control is nearly impossible; the muzzle climbs violently, making accurate fire beyond a few feet futile. It dramatically increases wear on the pistol's internal components and poses a significant safety hazard due to the loss of controlled, aimed fire. These devices are not precision instruments; they are novelty items that turn a reliable defensive tool into an uncontrollable bullet hose. For professional entities like law enforcement or military units with access to registered, select-fire Glock 18s, training emphasizes extremely short, controlled bursts—a technique nearly impossible to achieve with an aftermarket switch on a standard pistol frame.

Last updated: March 27, 2026