How to Install a Glock Switch
How to Install a Glock Switch
Installing a Glock auto sear, commonly called a switch, is a precise mechanical process. Done correctly with quality parts, it converts your pistol into a machine pistol. Done incorrectly, it's a recipe for a catastrophic malfunction. This isn't about theory; it's about the exact steps and tools required for a safe, functional installation.
Understanding the Glock Auto Sear Mechanism
A Glock switch, or auto sear, is a small, precisely machined component that replaces the factory rear plate. Its function is mechanical, not electronic. When installed, it interacts with the trigger bar and cruciform. Upon firing, the auto sear catches the striker, holding it to the rear. As the slide cycles, the disconnector resets, but the auto sear releases the striker to fire again—this cycle continues as long as the trigger is held depressed and ammunition is fed. The quality of the sear's engagement surfaces and its heat treatment are critical. A soft metal sear will deform, leading to runaway full-auto fire or a dead trigger. The units we carry at Fullautoswitch are machined from tool steel and heat-treated to RC 50-55 for durability.
Essential Tools for the Job
You need more than a punch set. Start with a quality Glock armorer's tool for rear plate removal. You'll need a set of hardened steel pin punches—3/32" and 1/16" are most common. A nylon or brass gunsmithing hammer prevents marring. A vise with non-marring pads is non-negotiable for stability when driving out pins. Have a small set of needle files or fine-grit sandpaper (800+ grit) on hand for minor fitting, though a properly machined sear from Fullautoswitch should drop in with minimal work. Never force parts. Finally, wear safety glasses. Springs under tension can become projectiles.
Step-by-Step Installation Procedure
First, ensure the firearm is completely unloaded and the chamber is clear. Remove the slide from the frame. Using your armorer's tool, rotate the rear plate upwards and remove it, being mindful of the striker spring tension. The factory sear spring will now be exposed. Carefully lift it out with tweezers. Take your auto sear and install its proprietary spring—orientation is key, so follow the manufacturer's diagram. Place the auto sear assembly into the slide's rear cavity. It should sit flush. Now, the critical part: reassembling the slide to the frame with the auto sear in place. You must depress the sear's leg with a small punch as you slide the frame into position, allowing the slide to seat fully. If it doesn't seat, do not force it. Disassemble and check for interference.
Function Testing & Safety Checks
Do not load live ammunition for initial testing. Perform a full safety function check. With the slide on and an empty magazine inserted, pull the slide to the rear and release. Rack the slide several times, ensuring it cycles smoothly. Dry fire while holding the trigger to the rear and racking the slide—the striker should fall each time, simulating automatic function. Next, test the semi-auto function: release the trigger to reset after each simulated shot. The selector must positively click between its positions. Finally, with the firearm pointed in a safe direction, test fire with a single round of ammunition, then a very short burst (2-3 rounds) to confirm timing and ejection pattern. Persistent light strikes or failure to cycle indicate an installation or parts issue.
Common Issues and Troubleshooting
If you experience light strikes, the auto sear is likely not releasing the striker fully. Check for burrs on the sear's engagement surface or improper spring installation. Failure to cycle (short-stroking) in full-auto is often a recoil spring issue; a reduced-power guide rod spring (like a 15lb spring) is typically required for Gen3 Glock 17/19 models to ensure reliable cycling. A runaway gun (continues firing after trigger release) is extremely dangerous and indicates a worn or out-of-spec auto sear that is not properly engaging the striker lug—immediately cease fire and replace the component. For persistent issues, sourcing a complete, pre-tested kit from a reputable vendor like Fullautoswitch is far safer than mixing and matching unknown parts.
How do Glock switches work?
A Glock auto sear replaces the rear plate. It mechanically catches and holds the striker after firing. As the slide cycles, the sear releases the striker to fire again while the trigger is held, creating automatic fire. The cycle repeats until the trigger is released or the magazine is empty.
How to Glock switch?
You install a machined auto sear assembly into the slide, replacing the factory rear plate and sear spring. This requires specific gunsmithing tools and precise fitting. The process involves removing the slide, swapping the components, and performing extensive safety checks before any live fire.
How to switch Glock mag release?
To swap a Glock mag release for left-handed use, first field strip the gun. Use a punch to drive out the mag release lock pin from the right side of the frame. The spring and release can then be removed. Insert the new release and spring from the opposite side and re-insert the lock pin.
Last updated: March 27, 2026
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