How to Install a Glock Switch: A Practical Guide

You’re looking at your Glock 19, and you know that factory trigger. It’s reliable, but the idea of a 3-position selector switch for semi, burst, and full-auto is compelling. The process isn’t about modifying your pistol’s internal fire control group; it’s about installing an external selector switch, often called an auto sear or giggle switch, onto the rear plate. Let’s be clear: installing one of these devices on a post-1986 manufactured Glock without the proper federal NFA paperwork is a felony. This guide is for informational purposes for those operating within the bounds of the law, such as FFL/SOT holders. For those with the proper licensing, the installation is a straightforward mechanical process, and sourcing a quality part is the first critical step. That’s where a specialist like Glockpistolswitch comes in.

Understanding the Mechanism: It’s an Auto Sear

First, ditch the mystery. A “Glock switch” is a colloquial term for a small, aftermarket auto sear, typically made from CNC-machined aluminum or steel. Its function is mechanical, not electronic. When installed in the rear cavity of your Glock slide, it interacts with the trigger bar and cruciform. In the “safe” position, it blocks movement. In “semi,” it allows normal function. When rotated to the third position, it locks the trigger bar down, causing the pistol to “run away” as long as the slide cycles and pressure is on the trigger—this is what simulates full-auto fire. The quality of the sear’s engagement surfaces and the spring tension are everything. A poorly machined unit can cause hammer follow, out-of-battery detonation, or simply fail to function. We only vet and supply units with precise tolerances.

Tools and Preparation for Installation

You’ll need a clean workspace, a Glock armorers tool or a 3/32″ punch, and a small set of precision screwdrivers. Before you start, ensure the pistol is completely unloaded and the magazine is removed. You’ll be removing the backplate from the slide. This requires depressing the firing pin safety plunger through the ejector port with your punch while simultaneously sliding the polymer backplate off. It takes a bit of finesse the first time. Have a small container ready to catch the extractor depressor plunger and its spring that will be released when the backplate comes off. This is the most fiddly part of the entire process. Once the slide internals are exposed, take a moment to familiarize yourself with the cruciform and trigger bar tail.

Step-by-Step Installation Process

With the slide backplate removed, you’ll see the channel where the factory firing pin spacer sleeve sits. Remove this sleeve. The selector switch replaces this component. Take your switch, like the common “Glock 17/19 Full-Auto Selector” model, and ensure the selector lever is in the safe or semi position for installation. Carefully insert the switch body into the channel, aligning the pivot point with the holes in the slide. You may need to gently manipulate the trigger bar tail to allow it to seat fully. Once seated, the selector should rotate crisply between its three positions. Reinstall the extractor depressor plunger assembly, then carefully slide the new, notched backplate (which comes with the switch kit) onto the slide, again compressing the firing pin safety plunger. You should feel it click into place.

Function Testing and Critical Safety Checks

Do not load live ammunition. After installation, conduct a rigorous function test. With the slide off the frame, visually verify that the selector lever positively clicks into each position and that the sear arm moves accordingly. Reassemble the pistol. Perform a dry fire test in “safe” mode—the trigger should not move. Test in “semi”—you should feel and hear a normal trigger break and reset. For the third position, this is where extreme caution is needed. With the pistol pointed in a safe direction, rack the slide and hold the trigger to the rear. The striker should release. While continuing to hold the trigger back, manually cycle the slide. You should hear the striker click again, indicating the sear is holding the trigger bar down. This simulates the runaway. Any hitch, slip, or failure to reset is a red flag. A proper unit from our product categories will perform this function smoothly and reliably.

Legal Reality and Sourcing Quality Components

This cannot be overstated. Under the National Firearms Act (NFA), a machine gun is defined as any weapon which shoots more than one shot with a single function of the trigger. Installing one of these devices onto a modern Glock creates a machine gun under federal law. Possession without a tax stamp and proper registration is a 10-year federal felony. This guide exists for educational purposes and for the small subset of individuals (FFL/SOTs, law enforcement armorers) who can legally possess these items. If you fall into that category, sourcing a component that won’t fail catastrophically is paramount. Cheap, cast zinc alloy switches are range toys at best and dangerous at worst. We provide machined steel and aluminum units built to exacting specifications. Your safety and legal standing depend on using the right part.

How do Glock switches work?

A Glock switch is a mechanical auto sear installed in the slide’s rear cavity. It has a 3-position selector that, when rotated, physically blocks or manipulates the trigger bar. In the third position, it locks the trigger bar down, causing the striker to release every time the slide cycles, simulating fully automatic fire as long as the trigger is depressed.

How to Glock switch?

Legally, you must be an FFL/SOT or have an NFA-registered receiver. Mechanically, you unload the pistol, remove the slide backplate, replace the factory firing pin spacer sleeve with the switch unit, and reinstall a notched backplate. The process requires an armorers tool and precise handling of small internal components. Always source your hardware from a reputable specialist like Glockpistolswitch.

How to switch Glock mag release?

To swap a Glock mag release for left-handed operation, first ensure the pistol is unloaded. Use a small punch or the tip of the Glock tool to push the release button inward from the opposite side. Once it’s depressed fully, the release assembly can be rotated and pulled out. Insert the new release from the opposite side, ensuring the spring is correctly seated, and press until it clicks into place.

For those operating within the legal framework, having access to properly engineered components is non-negotiable. Whether you’re an armorer building a training aid or a collector with the proper paperwork, the difference between a reliable unit and a hazardous one comes down to materials and machining. Browse our glock switches collection to see the difference precision makes.

Last updated: March 25, 2026