Glock Switch vs Binary Trigger: A Technical Breakdown for the Informed Shooter

The moment you pick up a modified Glock, the fundamental question isn’t just about rate of fire—it’s about control. A Glock switch, or auto sear, fundamentally alters the firearm’s fire control group to enable fully automatic fire with a single trigger pull. A binary trigger, like the popular Franklin Armory BFSIII, is a mechanical replacement that fires one round on the pull and another on the release of the trigger. The difference isn’t subtle; it’s the chasm between a machine pistol and a mechanically complex semi-auto. At Glockfullautoswitches, we deal in the former, and understanding this distinction is critical.

Mechanical Operation: Redesign vs. Retrofitted Mechanism

A Glock switch is a small, precision-machined component, typically made from hardened steel or aluminum, that interfaces directly with the factory trigger bar and striker system. When installed in a Gen 3 Glock 17 or 19, it allows the striker to reset and fall repeatedly as long as the trigger is held rearward and there is ammunition in the magazine. It modifies the core function of the FCG. A binary trigger is a complete drop-in trigger pack replacement. Its internal hammer and sear arrangement is designed to catch and release on both the pull and release stages. It doesn’t create an open bolt; it creates a two-stage, two-shot cycle that is entirely dependent on the shooter’s trigger finger rhythm.

Rate of Fire and Practical Control

This is where the rubber meets the road. A properly installed switch on a Glock 17 with a standard recoil spring can achieve rates around 1,200 rounds per minute. Control is a function of grip, stance, and magazine capacity—it’s a burst system in a handgun platform. A binary trigger’s rate is mechanically limited by the speed at which you can pull and release the trigger. A skilled shooter might achieve rates comparable to very fast semi-auto fire, but it will never match the cyclic rate of a true auto sear. For pure volume of fire, the switch is in a different category. Our customers at Glockfullautoswitches who seek that specific performance understand this inherent difference.

Legality and Regulatory Status: The Critical Divide

This is non-negotiable and must be stated clearly. Under the National Firearms Act (NFA), a Glock switch is classified as a “machinegun” and is strictly regulated. Possession of one not registered with the ATF prior to May 1986 is a federal felony. Binary triggers, however, are currently legally sold in most states as they are considered a semi-automatic fire control group—they require a separate trigger action for each shot. They are not classified as machineguns. This legal chasm dictates everything from procurement to use. Always, without exception, know your federal, state, and local laws before acquiring any modification.

Installation Complexity and Reliability

Installing a Glock switch requires detailed knowledge of the Glock’s internal anatomy. You’re modifying the rear rail and often the trigger housing. It’s not a drop-in procedure and requires specific tools and understanding to ensure safe function. A binary trigger, such as the Franklin Armory model for Glocks, is designed as a drop-in unit for Gen 3 models, replacing the entire trigger mechanism housing. Reliability differs too. A well-made switch, like the ones we inspect at Glockfullautoswitches, runs with the simplicity of the original design. Binary triggers introduce a more complex sear geometry that can be sensitive to ammunition, lubrication, and shooter technique.

Purpose and Practical Application

Your intended use dictates the choice. A binary trigger is a range novelty and a training tool for trigger reset discipline; it simulates a very fast follow-up shot. A Glock switch serves the singular purpose of converting a semi-automatic pistol into a fully automatic one. Its application is specific to that function alone. There is no overlap. If your goal is to understand and experience the mechanical operation of a select-fire system, the switch is the only component that delivers that authentic function. For those pursuing that path legally through the proper NFA channels, our shop offers the necessary components built to exacting standards.

Can you put a binary trigger on a Glock?

Yes, but only on specific generations. Companies like Franklin Armory manufacture binary trigger systems designed as drop-in replacements for Gen 3 Glock models (like the G17, G19). They are not compatible with all generations due to changes in the trigger mechanism housing design. It is a complete FCG replacement, not a simple part addition.

Why are Glock switches illegal?

Glock switches are classified as “machineguns” under the National Firearms Act of 1934 and the Firearm Owners’ Protection Act of 1986. Their sole purpose is to convert a semi-automatic firearm into a fully automatic one. Possession of an unregistered switch is a federal felony, as they fall under the same regulatory category as a factory-made machine gun.

Why does Glock have 2 triggers?

A standard Glock does not have two triggers. This is a common misperception. The Glock’s “Safe Action” system features a trigger safety—a small lever in the center of the trigger shoe. This is an internal safety mechanism, not a second trigger. It must be fully depressed to allow the main trigger to move rearward and fire the pistol.

The choice between a binary trigger and a Glock switch defines the capability of your firearm. For the enthusiast seeking the definitive performance of a select-fire system through legal NFA channels, the auto sear is the only component that delivers. Browse our glock switches collection to see precision-engineered components built for those who understand the difference.

Last updated: March 27, 2026