Best Binary Triggers for AR15: Top 2 Picks

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By Dennis Howard •  14 min read

One of the first things any AR-15 owner usually considers is an upgrade to the factory trigger system in their rifle. Most shooters want to improve the quality of the trigger action, the trigger pull, and the trigger release. One upgrade that is usually considered by an AR-15 owner is a binary trigger installation. Finding a binary firing system for your AR-15 needs to be carefully considered.

Best Binary Triggers for AR15

A true binary trigger works differently than a standard trigger. Like a standard trigger, the rifle will fire when the trigger is pulled rearward. However, a binary trigger also fires one round when the trigger is released back to the normal reset position.

Binary trigger systems are currently legal in the United States. Installing a binary trigger in your AR-15 does not turn it into an “automatic weapon” under the current BATFE rules.

In this review, we will look in some depth at the binary trigger systems that are currently on the market. Each operates a bit differently and offers unique features that may fit your needs. Specifically, we will seek to answer these questions:

The Best Binary Triggers Currently Available

The primary question we want to address is which of the currently available binary trigger systems for AR platform firearms is the best choice. These trigger groups allow some functions that a standard drop-in trigger group can provide. In many cases, the differences between one binary trigger and another are minimal.

After you read this article, you will have a better understanding of the features, functions, benefits, and disadvantages of installing a binary trigger system in your AR-15 rifle or pistol.

1. Franklin Armory Binary Triggers

Franklin Armory wasn’t the first to engineer a binary trigger. However, it was Franklin Armory who coined the phrase “Binary Trigger” which has since become the industry standard nomenclature for these pull-and-release style trigger systems.

Currently, Franklin Armory has two binary trigger systems specifically for the AR-15 platform, and they continue to own the majority of the binary trigger market. These are, undeniably, the top of the line when it comes to binary triggers.

Franklin Armory AR-C1 binary trigger with curved metal trigger for your semi automatic weapon

Franklin Armory® BFSIII® AR-C1 and BFSIII AR-S1

Of the two binary triggers manufactured and sold by Franklin Armory, the BFSIII AR C1 has the most traditional look. The AR-S1 model is equipped with a straight flat-faced trigger giving a more custom look to your AR. When installed in an AR-15 lower receiver, the curved trigger profile looks almost like a standard curved trigger. There is no visible indication that the trigger connects to a binary firing system.

Among the other features of the BFSIII AR C1 trigger system are:

The Franklin Armory BFSIII AR C1 trigger and the BFSIII AR-S1 trigger assembly can bring your AR-15 platform to a new level of functionality and enjoyment. This legal trigger system from Franklin Armory Triggers can get you into the world of binary shooting easily and quickly.

Franklin Arsenal BFSS AR-S1 binary triggers feature a straight trigger for tactical gun enthusiasts
Trigger Operation with the BFSIII AR-C1 or BFSIII AR-S1

Operating either of these Franklin Armory binary trigger systems doesn’t take a lot of retraining or readjustment from your normal shooting routine. The safety selectors typically function properly without adjustment. Each Franklin Armory binary trigger includes a red operations decal that you apply to your AR lower before installing the safety selector. The enhanced safety switch has three positions:

Franklin Arsenal BFSIII binary triggers can be used in semi automatic mode or in binary selection
Shooting with a Franklin Armory BSFIII Binary Trigger System

It does take a bit of practice to shoot the Franklin Armory Binary triggers efficiently and accurately. Timing is a critical part of shooting any binary trigger. A certain cadence must be struck between trigger pull and trigger release for the rifle to function properly.

When the Franklin Armory binary trigger is in binary mode (position three on the selector switch) the rifle is in hot mode and should be handled with the usual caution and safety in mind. Each time you pull the trigger a round will be fired just like a normal semi-automatic rifle. However, when shooting binary, when you release the trigger back to the normal reset position, another round will be fired.

Finding the Rhythm

Of course, one of the fun things about binary triggers is the rapid rate of fire you can gain. Dumping an entire 30 round mag in under 20 or 3 seconds can put a grin on almost any shooter’s face. What could be more fun than training to shoot?

Keeping Things Safe

If you need to stop shooting with the selector set to binary and the trigger pulled, you must change the selector switch to either semi-auto or safe before you release the trigger to prevent another round from firing.

In the End

If you choose to install a Franklin Armory binary trigger in your AR platforms, you won’t get much argument from me. The Franklin Armory BFSIII AR-C1 trigger is the choice I made for my 300 Blackout. It has operated flawlessly on the firing range and in the field.

  • Easy installation for most shooters.
  • A smooth trigger pull of 4.5 lbs +/- 0.5 lbs.
  • The trigger performs a positive reset on the release phase .
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2. FosTecH Echo Trigger Systems

Fostech is a family-owned and operated company located in the heartland of the U.S. in southern Indiana. From rifle accessories to fully assembled rifles, Fostech has a reputation for quality and service.

Fostech competes in the binary firing system market with its Fostech Echo AR-II triggers and the Echo Sport Triggers. The Echo AR-II trigger systems are uniquely designed drop-in trigger systems for your AR platforms. The Echo Sport trigger is a less expensive model that has several unique features of its own.

Fostech Echo Sport Trigger

Fostech Echo Sport binary triggers

The Echo Sport Trigger from Fostech is an economical pull-and-shoot trigger that gives you access to binary modes on your AR-15 rifle. Like all binary systems, there is a choice of semi-auto mode or a pull-and-release binary option.

Fostech is known for its attention to detail and quality control. The list of features with the Fostech Echo Sport Trigger is a good indication of what you are purchasing:

Fostech Echo Sport AR Trigger Kit for standard tigger pin size complete with trigger spring

The chief difference between the Fostech Binary Firing system and the Franklin Armory models is the way the mode is selected. Franklin armory binary triggers use the safety selector switch to change modes. The Fostech Sport trigger puts another control on the rifle just above the trigger. This paddle is moved from side to side to switch from standard mode to echo mode. The rifle safety remains as it is and unmodified.

Operating the Fostech Sport Trigger System

In the semi-auto mode, you won’t notice much difference with the Fostech Sport trigger installed. Some shooters report that the trigger pull maybe a little heavier than a standard trigger pull. This may take some getting used to but a little time on the shooting range should soon overcome any unfamiliarity.

Changing from semi-auto mode to the echo settings isn’t hard. If you are familiar with a cross-bolt safety on a rifle, you can easily visualize how the selector switch operated. Push the paddle to one side and you place the rifle in standard semi-automatic shooting mode. Push the paddle above the trigger the other way and you are instantly ready to shoot in pull and release mode.

Safety and Selector Operation

If you need to stop shooting in the middle of the pull and release cycle, simply hold the trigger back and push the paddle selector to the semi-auto position and then release the trigger. Remember to practice all of your gun safety protocols when making this change to ensure that an unintentional discharge sends your bullet safely downrange.

Timing for Greatly Reduced Split Times

I have to admit that one of the great reasons for the expense and time of installing a binary firing system in any of my rifles is the fun of lighting up the shooting range with a rapid and sustained mag dump that nears the speed of a fully automatic weapon.

There is some skill and practice required to get your binary trigger work to the point that you can make perform this kind of action. Your timing on the trigger system must be smooth and consistent. However, when you find the sweet spot with your trigger finger, the operation becomes almost automatic.

The Downside of the Fostech Sport Trigger

Choosing a Fostech Sport trigger does come with some downsides. Before you elect to spend your hard-earned gun budget on a Fostech Sport Trigger, you should be aware of these additional requirements:

There is no doubt that the Fostech trigger systems are exceptional pieces of firearm engineering. There are significant differences with the Franklin Armory Binary triggers. Some shooters see the Fostech system as too complicated.

  • High-quality manufacturing ensures proper fit and installation.
  • The kit comes with all the necessary parts, trigger springs, pins, and tools to perform the installation.
  • Requires some skill and understanding of the AR-15 platform to install this trigger assembly.
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Fostech Echo AR II Trigger

At the top of the Fostech line of binary systems is the Echo AR II Trigger. Unlike the Echo Sport, the Echo AR II is a true drop-in trigger kit. Remove your old trigger assembly, drop in the Echo AR II kit and replace two pins. The AR II trigger system shares a lot of the same features as the Echo Sport Trigger. However, there are some distinct differences.

Fostech AR II requires standard trigger pin size
Mode Selection on the Echo AR-II Binary Firing System

Unlike the Echo Sport Trigger system that uses a cross paddle design to select modes, the AR II binary firing system puts the mode selection on the AR safety selector, much like the Franklin Arsenal systems. In practice, the Echo AR II safety selector switch offers the positions.

Echo AR-II trigger fits most guns with an AR-15 lower

Many shooters find the safety switch a more familiar means of selecting the firing mode when shooting their AR platforms. In my opinion, this is a much more simple mechanism than the cross-bolt style selector switch on the Fostech Echo Sport trigger system.

Meeting the Rifle Requirements for the Fostech Echo AR-II Binary Firing System

Consulting the Fostech website for information reveals that the technical requirements for installing a Fostech Echo AR0II trigger system may be a barrier. Fostech makes these recommendations if you install the AR-II system in your rifle.

In addition, only lowers with standard trigger pin size will work with the Fostech Echo AR-II trigger system. Carbon fiber and polymer lower constructions usually have extra support material that often interferes with the trigger operation.

In the End

With all that said, how do I feel about the Fostech Echo AR-II binary firing system? I think it is a well-engineered piece of equipment. By all accounts when the Fostech AR-II system is installed correctly, it functions reliably and efficiently. However, if your lower isn’t mil-spec and you don’t adapt to the other requirements, the Fostech AR-II may give mixed results.

  • Safe Setting puts the rifle in cold mode. The rifle should not fire at all in this mode.
  • Echo Mode Setting activates the binary firing system.
  • Semi-automatic mode allows the rifle to fire in a traditional way.
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The Truth of the Binary Firing System Market

Unfortunately, there are only two real choices in the Binary trigger market. Franklin Armory and Fostech are your only two choices if you are searching for a binary trigger for your AR platforms. Both make good systems. I prefer the Franklin Armory Binary Trigger system. I feel like it is simpler and more robust than the Fostech system.

The Other Things You Should Know About Binary Firing Systems

While the BATFE has approved the sale of the binary firing systems in this article, many local jurisdictions make the purchase and ownership of binary triggers illegal. Both Franklin Armory and Fostech refuse to ship to an address in these proscribed zones. If you live in one of these areas, be sure to check the legality of a binary firing system in your area.

If there is any question about the legality of binary firing systems in your area, be sure to check with the local authorities to ensure you stay with the local laws.

My Other Problems with Binary firing Systems

I have one other problem with binary firing systems. The cost. Not the cost of the triggers, but the cost of the ammunition I tend to expend when I take a rifle with a binary trigger to the shooting range. It is all too easy to burn through several hundred rounds in just a few minutes. My reloading time has gone up as I try to keep up.

You should also be ready to get a lot of attention from other people on the net. As soon as you hit your rhythm and your file starts to spit out a string of rapid shots, attention is going to be on you. Everyone will assume you have a machine gun and start to migrate in your direction. Unfortunately, the range management may also take an interest, as many ranges have banned both fully automatic weapons and those outfitted with binary firing systems.


For what it is worth, my choice of binary firing system is the Franklin Armory BFSII AR-C1. I like the feel and look of the curved trigger. The installation was simple and quick. I also like that the trigger comes with a buffer and buffer spring. Binary firing systems are fun and do have some real uses in competitive shooting and hunting. I hope that you find this information useful. Good shooting.

Dennis Howard

A life long hunter, fisherman, and outdoorsman, after surviving a devastating tornado in his home town, he saw the effects on people's lives as they struggled to cope. He built his first bugout bag a few weeks later and has been a dedicated prepper/survivalist since that time. After a career as a fireman, Dennis opened a retail store (FFL approved) catering to the military, law enforcement, and like-minded individuals. The store built their own AR platforms. Furthermore, Dennis was also an NRA instructor in both long gun and handgun as well as a certified range safety officer. Read his full interview here.