What Is a switch for glock? The Technical Breakdown

A glock switch, properly termed a selector switch or auto-sear, is a small, precisely machined component that replaces the factory rear plate on a glock pistol. When installed, it modifies the firearm’s fire control group to enable fully automatic fire. This isn’t a modification for casual plinking; it fundamentally alters the weapon’s function, turning a semi-automatic pistol into a machine pistol. The most common and infamous example is the “Glock 18” configuration, but aftermarket switches are designed for models like the glock 17, 19, and 26. At Glockswitchkit, we provide the components for those who understand the serious engineering and responsibility involved.

The Core Mechanism: How a glock Auto-Sear Works

To understand the switch, you need to know how a glock normally fires. The trigger bar has a cruciform sear that engages with the striker’s sear shelf. When you pull the trigger, the bar drops down, releasing the striker. A glock switch introduces a secondary, spring-loaded sear—the auto-sear—into the equation. This sear intercepts the trigger bar after the first shot. As the slide cycles, it resets the auto-sear, which then immediately releases the trigger bar again, creating a continuous cycle as long as the trigger is depressed and ammunition is available. The physical switch on the backplate simply engages or disengages this auto-sear from the fire control group. It’s a deceptively simple mechanical solution to a complex timing problem.

Common Models and Compatibility

Not all Glocks are created equal for this modification. The platform must be a striker-fired, double-action-only model. The most compatible generation is Gen 3, due to its widespread parts availability and well-documented internal geometry. We primarily see switches for the full-size and compact frames: the glock 17 (9mm) and glock 19 (9mm) are the most popular. Subcompact models like the glock 26 can also be fitted, but the smaller internal space presents unique challenges. It is crucial to match the switch to your specific model and generation; a switch for a Gen 4 glock 19 will not function correctly in a Gen 3. You can browse our categorized switches to find the exact fit for your pistol.

Installation and Function: What to Expect

Installing a switch requires complete disassembly of the glock‘s slide. You remove the factory rear cover plate, install the switch assembly—which includes the new rear plate, the auto-sear, its spring, and often a modified slide cover—and reassemble. Once installed, flipping the selector to the “auto” position allows for fully automatic fire. The rate of fire is extremely high, often cited between 1,200 and 1,500 rounds per minute for a stock glock 17. This empties a standard 17-round magazine in under a second, making controlled bursts nearly impossible without extensive practice and specialized training. This isn’t an upgrade; it’s a complete transformation of the weapon’s capabilities.

Legal Considerations and Responsible Ownership

This is the most critical section. Under the National Firearms Act (NFA), a machine gun 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. Installing a switch on your glock immediately creates a machine gun as defined by federal law. Possession of such a device, unless it is registered in the National Firearms Registration and Transfer Record (NFRTR) and the appropriate tax stamp is paid, is a felony punishable by up to 10 years in prison and $250,000 in fines. Glockswitchkit sells components to qualified entities and individuals operating within full compliance of all federal, state, and local laws. It is the buyer’s sole responsibility to ensure their build is legal.

Product Recommendations for Builders

For builders committed to a legal, registered NFA project, component quality is non-negotiable. A poorly machined auto-sear can lead to out-of-battery detonations or runaway full-auto fire. We recommend our G17 Gen3 Precision CNC switch Kit. It’s machined from 4140 steel, heat-treated, and includes all necessary springs and the selector lever. For those working with a glock 19 platform, the G19 Gen4 Drop-in Assembly is pre-timed and requires minimal fitting. Both are available through our store alongside the necessary jigs and tools for a proper installation. Remember, this is precision gunsmithing, not amateur hour.

What is a switch for glock?

A glock switch is an aftermarket auto-sear assembly that replaces the rear plate on a glock pistol. When engaged, it modifies the fire control group to enable fully automatic fire, converting the semi-automatic handgun into a machine pistol. It is a regulated NFA item under federal law.

What is a switch for a glock pistol?

Specifically for a glock pistol, it is a mechanical device containing a secondary sear. This sear interrupts the normal firing cycle, causing the pistol to continue cycling as long as the trigger is held rearward. It physically mounts to the rear of the slide where the standard cover plate is located.

What does a switch for glock look like?

It typically looks like a slightly enlarged rear cover plate for the glock slide, often made of metal. It will have a small, protruding selector lever or switch that can be flipped between two positions, usually marked with symbols like “•” for semi and “•••” for auto. The internal auto-sear is a small, hook-shaped piece of metal.

If you are building a legally registered machine gun and require high-quality, reliable components, browse our glock switches collection at Glockswitchkit. We supply the precise parts for serious builders.

Last updated: March 25, 2026