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What Is A Binary Trigger?

binary trigger

Put simply, a binary trigger is a type of semiautomatic trigger with two firing modes: semiautomatic and binary.

Semiautomatic is self-explanatory; it’s the standard trigger type that fires one round from your gun per trigger pull. A binary trigger setting fires two rounds with each pull of the trigger – once when you pull the trigger and once when you release the trigger.

All binary triggers are classified as trigger modifications. It’s very rare to find a firearm with a binary trigger installed by default. Most binary triggers are selectable. Meaning you can switch between semiautomatic and binary firing modes without being stuck in binary forever. 

How Do Binary Triggers Function?

Firing an AR-15 with a binary trigger at a shooting range

Firing .223 ammo with a Smith & Wesson AR-15 equipped with a Franklin Armory binary trigger.

To grasp how binary triggers work, let’s go over how semiautomatic standard triggers function.

In short, a regular semiautomatic trigger works when a trigger sear drops to release the firearm hammer. The hammer hits the gun’s firing pin, which triggers a small explosion in a loaded cartridge, propelling the round from the barrel of your firearm.

After you fire with a semiautomatic trigger, your gun’s hammer re-cocks, and the trigger disconnector holds the trigger back or in a rearward position. As you release the trigger, the disconnector then releases the hammer, allowing the sear to catch the hammer once more.

That’s how a semiautomatic trigger operates. A binary trigger, as its name suggests, uses two sears instead of one, allowing for dual trigger movements. When you pull a binary trigger, your hammer re-cocks immediately. The disconnector then grabs the hammer to prevent any automatic firing.

But as you release the trigger, the trigger’s secondary sear grabs the hammer again. This second sear drops to release the hammer once more and fire a second round. As you use a binary trigger, you’ll indeed see the firearm hammer snap forward twice in rapid succession (unless you hold off on releasing the trigger for whatever reason).

Most quality binary triggers will allow you to switch back to the semiautomatic setting while you are holding the trigger down. This allows you to switch between binary and semiautomatic firing modes “in-between” the binary trigger’s second shot, so to speak.

Why Use a Binary Trigger?

a photo showing binary trigger parts

What’s in the box? Hammer, trigger assembly, alternate weight springs, selector switch, medium & heavy buffer springs, and installation accessories.

If all binary triggers do is add a secondary shot to the end of your trigger pull, why would anyone bother using them? After all, binary triggers take a lot of practice to get used to and can mess up your established shooting habits.

Even though they seem a bit funky, binary triggers can provide several serious benefits or advantages for competitive shooters. In many target shooting competitions, speed and shot placement are the two most important factors when being graded.

If you have a binary trigger, you can pull off two shots in rapid succession faster than anyone using a standard semiautomatic trigger. For this reason, only some competitions allow them. They provide a flat speed increase for skilled marksmen who can use these triggers competently.

In certain home defense situations, binary triggers may also be advantageous. Since home defense or personal defense situations are often tense and adrenaline-filled, it can be tough to remember to pull the trigger multiple times to take down a larger opponent.

A binary trigger takes thinking out of the equation, allowing you to put two rounds into an attacker immediately. When used with a small, self-defense sidearm, it can literally double its stopping power. Although, it also doubles the recoil.

Are Binary Triggers Legal?

Technically, yes. According to federal law per the Bureau of Alcohol, Tobacco, and Firearms, binary triggers are legal modifications to firearms.

But in the United States, there are two sets of laws you have to keep in mind: federal and state laws. States have different opinions on binary triggers, so these modifications are only legal in some states. At the time of this writing, binary triggers are illegal in:

Delaware is a special case. In this state, you can get certain binary triggers for pistols or non-rifle firearms like shotguns. But you can’t get binary triggers for rifle firearms.

As you can see, binary trigger laws can be a little complex. Be sure to double-check the laws in your state before looking to purchase a binary trigger so you don’t get in trouble.

What if You Have a Binary Trigger and Are Traveling Through Illegal States?

Then you’d better hope you don’t get stopped by any state police. The state police will have a right to arrest you if they catch you with a binary trigger. Sadly, even if you are simply passing through. Again, this demonstrates the importance of being knowledgeable of up-to-date firearm laws before traveling with any heavily modified guns.

Should You Use a Binary Trigger?

a photo of a selector switch on an ar15 rifle

If you’re willing to give up some accuracy for speed, a binary trigger can be an effective tool for increasing your rate of fire.

That depends.

As described above, these triggers do provide several specific advantages. They can be good choices for home defense or target shooting competitions.

However, those who use firearms primarily for hunting probably won’t find very much use for binary triggers. Most of the benefits are lost on hunting rifles. Binary triggers can mess up your accuracy, as they produce two recoil bumps instead of one.

Additionally, anyone using a binary trigger will need to put a lot of work into mastering this modification. You’ll have to work hard on building up new muscle memory and recoil control. You’ll need to be able to quickly reset your sights and take another shot after the first two bullets have been expelled from the barrel.

A binary trigger might be a good modification for your firearm. It depends on your preferences. But no matter what you plan to use it for, you’ll need to practice with your binary trigger for it to be a worthwhile addition. 

Getting Triggered

Ultimately, binary triggers can be effective gun modifications. Of course, you’ll need to put the practice in to become competent and safe with them. It will allow you to increase your rate of fire by sacrificing some accuracy. Furthermore, you should double-check that binary triggers are legal in your state before purchasing any, especially online.

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