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Franklin Armory BFSIII Binary Trigger [Review]

The Franklin Armory Binary Trigger allows a shooter to simulate full-auto fire without the expense and NFA restrictions of a truly fully-automatic lower. Find out more about this cool piece of engineering (and see why it might be going away forever).

    Sometimes when we talk about serious topics like home defense and concealed carry, and even improving skills for competition, we neglect to think about the raw, unadulterated fun that can be had (safely and legally) with firearms.

    And of course, when it comes to firearms, is there anything much more fun than dumping a magazine on full-auto down range?

    Full-Auto Mag Dump, David Hunter
    Full-Auto Mag Dump, David Hunter

    Of course, we puny civilians will have a hard time owning anything full-auto.

    Enter the Franklin Armory BFSIII Binary Trigger to change that.

    Normally, a full-auto AR-15/M4 is going to run you somewhere around $4,000 (if you have the dealer’s license for a Dealer Sample) or $20-30,000 for us normal folk, plus a tax stamp, and a long wait period. This guy above costs around $400. 

    Let’s take a look at just what this fun little range toy does.

    **Update 3/26/2018**: Since I wrote this review, new legislation has been proposed to ban bump-stocks and binary triggers as well as other similar devices in many states following the use of a bump stock in the Las Vegas shooting, and such devices are now banned from appearing in YouTube videos. 

    They are also illegal in Florida, Washington, Massachusetts, New Jersey, and other states, with legislation to expand restrictions on the table in more places. 

    Be sure to check your local, state, and even federal laws before purchasing. It may come to pass that purchasing these things now will allow you to keep it later and it’ll be grandfathered in under new legislation, but you may also have to surrender it, depending on your local laws. 

    Something to keep in mind. I don’t want anyone (particularly gun owners) angry at me because I recommended they buy something they ended up in legal trouble over, or had to surrender without compensation. 

    **Update: 12/19/2018** Due to new Federal restrictions, bump-stocks will become illegal to possess in 90-days. This is currently being challenged in court but that may or may not void the order.

    Until such time, assume bump-stocks will be illegal soon. As of this update, binary triggers are NOT a part of the new ruling banning bump-stocks on the Federal level–but binary triggers remain illegal in some states due to state-level law. Check your local laws before buying!

    What is a Binary Trigger?

    A binary trigger is a drop-in replacement trigger that allows you to simulate full-auto fire in a semi-automatic weapon. This thing dramatically increases the fire rate of a semi-automatic AR-platform firearm.

    Is it as fast as a true fully-automatic weapon? I don’t exactly have an M4 on hand to compare, but looking at my splits with shot timer, I’m getting about 400 rounds per minute (obviously with a 30 round mag) which is a little under half the fire rate of a true full-auto rifle.

    That being said, it is a marked increase over a regular semi-automatic rifle, so you are getting what you pay for. It’s a $400 solution to a $4,000 (minimum) problem, but for all that it works damn well.


    I’ve installed, swapped, changed, replaced, and repaired literally hundreds of triggers in my day, and this one was neither the easiest nor the hardest one to work on. I would say if you can follow our guide to building an AR-15 lower, you’ll be fine.

    It took me about thirty minutes, and most of that was getting the previous trigger out of the gun I tested it in (and finding my freaking punches that rolled under my bench at some point). 

    bsf iii component view
    All the parts and pieces you get with the BFSIII

    How Does it Work?

    Binary triggers like the Franklin Armory BFSIII work by releasing the sear on the pull and release of the trigger when in binary mode, though you can also easily flip the three-way fire selector to regular semi-auto.

    This effectively doubles your fire rate and can give you some very close two round groups, to the point where I could land two hits in the A-zone at 25 yards with one trigger pull.

    Here’s Franklin Armory’s take:

    “The revolutionary Binary Firing System™ will be appreciated by three gun competitors, tactical shooters, and recreational enthusiasts. It features a three position selector that allows the user to switch from Mode 1 for Safe, Mode 2 for traditional Semiautomatic Mode, or Mode 3 for Binary Mode. In Binary Mode, the firearm will discharge one round with every function of the trigger whether a pull or a release. A user can negate the round that would otherwise be fired during the release function by simply moving the selector back to Mode 2 and then safely releasing the trigger.”

    Which of course sounds great, but how does it perform in the real world?

    Shooting the Franklin Armory Binary Trigger

    So, with that in mind, how does this thing really shoot? Pretty well, it turns out.

    Now, don’t get me wrong, it doesn’t feel as nice as a say, a good Geissele or Timney trigger, not even one you can get for half the price of the BFSIII.

    at Brownells

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    That being said, it is a marked improvement over a standard mil-spec trigger from a parts kit in every way, Binary Firing System be damned.

    As far as actually using the thing at the range, if you want to rip crisp, clean, easy double-taps, this thing is awesome. 

    I like being able to use my rifle in a regular semi-automatic mode. I like being able to switch to Binary mode and rip a few quick shots off at a target and the hyper-rapid ping-ping on steel is addicting.

    If you’re a competitor, you could do better. I don’t actually agree with Franklin Armory’s assertion that this thing has any real use in a competitive environment.

    3gun shooting competition
    This rifle doesn’t need a binary trigger, I promise.

    It’s not going to give you a real advantage unless you’re holding the second round and using it to engage a target on the release of the trigger, which seems unsafe to me.

    Definitely, don’t try that while you’re moving. Tripping while holding a loaded rifle is never a good thing, especially when you have your finger near (or worse on) the trigger, but this danger is amplified a thousand-fold when the release of the trigger also sends a bullet down-range.

    Practical Applications

    In short… eh? Maybe. Kinda. It depends. But not really, no.

    When I say it depends, I say that because it depends on whether or not you’re actually getting it to defend yourself, or you’re trying to convince a spouse to let you spend $400-$500 on one by extolling its practical uses.

    If you haven’t trained with a full-auto weapon, it’s going to be more of a hindrance than a help in almost any practical defense situation.

    I suppose, yes, if you need to suppress an intruder’s position so a family member can flank them and take them out, maybe it’s better? You could at least make the argument.

    But that situation has happened a grand total of zero times in a home defense scenario. You are not John Wick.

    John wick 2 training
    Keanu Reeves shoots better than you (and me too, probably)

    I cannot conceive of a case where I’d want one of these in a self-defense rifle over a good precision trigger.

    It’s also worse in every way except the rate of fire in a competition setting. No one has ever needed full-auto in a 3Gun match, and if anything you’re going to be wasting ammo, time, and effort if you’re using binary mode.

    And if you’re not using binary mode, why not just get a better, purpose-built 3Gun trigger? 

    It’s not a particularly precise trigger, with a little bit of grit and a break that’s just shy of what I’d consider acceptable on a competition gun. 

    So, what are the real practical applications? Well, it’s a great way to drop a lot of brass on the floor.

    Shooting Range Spent Brass
    The BFSIII also works with 9mm and .22 AR’s that take a standard trigger.

    Beyond that, it is really, really, really fun. Like a lot of fun. Definitely worth the $400.

    And I think, if we’re honest with ourselves, most of us gun owners don’t have a practical use for all the cool toys we have lying around. I know I sure don’t.

    So, taking an honest look at this thing, it’s not really necessary. It’s not going to give you an edge in a competition, or an edge over someone seeking to do you harm.

    You should absolutely buy one though. It’s an absolute blast, and if you’ve ever wanted to experience fully-automatic fun at the range, this is the cheapest path to entry you’re ever gonna have.

    Parting Shots (and another warning)

    Overall, I quite like the BFSIII, I think it’s a great piece of engineering, and it absolutely does what it claims to do. I take issue with some of Franklin Armory’s marketing on what this thing is actually good for, but I think that’s more of a case of wishful thinking on their part than it is actual malice or an attempt to deceive anyone. 

    All in all, it’s a great little piece of kit, American made, and it’s fun as all get out. It’s also one of the best ways to turn money into noise at the range, and that alone makes it worth the cost of admission.

    Now, I do have to again bring up the fact that there’s legislation being bandied about right now that would ban these devices. So check your local laws and make sure you’re not committing a felony.

    But as long as it is legal for you to own, I highly recommend it–it’s just too fun not to have! Especially if you pair it with a .22 LR AR-15 so that all of that binary shooting doesn’t run you bankrupt.

    Take a look at our Best AR-15 in .22LR article for some great recommendations!

    at Brownells

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    I’m curious to see what you all think about this so be sure to drop me a line in the comments letting me know how you feel and let me know what you think about the BFSIII Binary trigger in general.

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    34 Leave a Reply

    • Commenter Avatar
      Clarence Waters

      Bought the full lower shot maybe 75 rounds and the selector switch on the left side fell off. Junk

      January 5, 2022 9:22 am
    • Commenter Avatar
      Roger Zelinsky

      So, if I understand correctly, the device releases the sear when the trigger is pressed and when it is released/reset? What if I don't want the second shot but have already pressed the trigger? How do I back out of the second shot?

      May 21, 2021 3:42 pm
      • Commenter Avatar
        joey franko

        You just put the ambidextrous selector back into semi and it cancels the release shot. I got one. But the article has made me realize how unsafe this trigger could be. The first time I shot it , I pulled the trigger twice, it shot 4 rounds so fast it caught me off guard and the barrel began to rise. Fortunately when I tested it I was shooting into soft soil at my home. I recommend a nice smooth trigger to the bsf111. Good luck

        May 22, 2021 5:00 pm
      • Commenter Avatar
        Carl Ramsey

        You switch it back to regular semi-auto (position 2) then release the trigger.

        July 8, 2021 5:46 pm
      • Commenter Avatar
        Pablo Mee

        If your in "BINARY MODE" & squeezed the trigger & sent a round down range, but have decided that you don't want a second round fired upon the release of the trigger; you simply switch your selector back to "SEMI" while you have the trigger depressed & you will be back in semi auto & won't fire that second round on the release of the trigger

        October 20, 2021 6:01 pm
    • Commenter Avatar
      Pit Viper

      I'll have to argue about $400 being the cheapest way to entry in regards to experiencing full auto at the range. There are gun ranges out there that rent full auto rifles. Bud's in Sevierville TN is an example.

      April 14, 2021 5:07 pm
      • Commenter Avatar

        Late response, but I think the author meant that this is the cheapest entry into owning that experience; not-really full-auto and all. Shame that it's so expensive to buy a true full-auto firearm with the way they've been regulated.

        April 30, 2022 11:24 am
    • Commenter Avatar

      I disagree about it not having a practical use; such a weapon can be used for home defense from behind a solid fortified wall or barrier(8-10 feet high). Given the current status of anarchy in Portland, Seattle, Atlanta, etc. such a barrier makes sense to mitigate ricochets into one's surrounding neighborhood or a neighbor's wall. I'm speaking of and describing T-wall type constructs as seen in Iraq and other hotspots. When rioters and looters come over the wall after you at home you're gonna need every advantage to neutralize that threat you can get, an Echo trigger gives you the edge.

      August 21, 2020 2:58 am
      • Commenter Avatar

        I the best application is mainly to have in the event of a major societal breakdown, like the loss of the rule of law, a civil war, major invasion from foreign army, or an EMP attack. Otherwise, you would be in major legal trouble if you use it in a self defence situation.

        November 14, 2020 8:38 am
    • Commenter Avatar

      Just my opinion but I think these are pushing the envelope as far as what they will banned next. I won't be buying one as I would rather have a nice smooth 3.5lb. 2 stage which is what's in my go build. I am sure I can get enough rounds off ACCURATELY with my setup to defeat any threat. Unless you are talking about critters from Star Ship Troopers. Then we are all screwed. But that is just my opinion. Go for it if you got the ammo and $$. Just hope you won't be surrendering it one day.

      July 12, 2020 2:08 pm
    • Commenter Avatar
      Craig Boatright

      I’d love to have a binary trigger, but how does it affect the barrel ?

      May 15, 2020 4:08 pm
    • Commenter Avatar

      I would be interested to know how this product compares to a hell-fire trigger attachment. What are the pros and cons of each, aside from one being 1/8th the price of the other.

      April 10, 2020 10:05 am
    • Commenter Avatar

      Why would you ever surrender any type of firearm or firearm tech? I would rather die. If you aren’t willing to die for your beliefs, you don’t have any beliefs.

      January 22, 2020 2:05 am
      • Commenter Avatar

        I don't think this applies here, but I will maintain that vanilla is better than chocolate ice cream. I wouldn't die for it, but it is still important.

        June 24, 2020 10:33 pm
    • Commenter Avatar
      Jo Do

      I can't see the bad in having one of these in a MILITIA team, or SHTF group, adds significant suppression fire to your group's capabilities

      December 23, 2019 4:47 pm
    • Commenter Avatar

      It’s fun no doubt and a ban is coming for sure. They’ll never stop CNC milling or 3D printing though. Practicality wise? Meh. You can shoot off enough with a regular trigger to stop most threats even SHTF zombie apocalypse type situations. Strength then will come in numbers. 3 guys with regular ARs can neutralize one guy with a binary trigger real fast. Personally I don’t think the safety issues overcome its fun factor. Having to hold that trigger and move the safety to come off binary unless you’ve emptied your mag is let’s just say it - dangerous. You use this thing in any self defense situation and don’t get it exactly right your a$$ is grass. You’re also inviting the cops out to your place when all your neighbors who think they’ve heard a machine gun legal or not going off call 911 and you know someone will. Every neighborhood no matter how far you think you live from civilization has one. I do. He keeps trying to lower the speed limit because he’s just a dick.

      December 8, 2019 12:41 pm
    • Commenter Avatar
      Gene Decker

      I have the franklin binary on my dpms ar15 build and absolutely love it

      November 15, 2019 11:06 pm
    • Commenter Avatar

      So, does the Franklin Armory BFS require the purchaser to buy a fully automatic BCG, as the Fostech BFS requires? I had planned on purchasing a Fostech BFS, until I found that little piece of information. What is the real truth here?

      November 12, 2019 11:54 am
      • Commenter Avatar

        Yes you need to full auto bolt carrier but this is the reason why you want Echo Deco has a heart of it interacts with the bolt carrier what it does is prevents hammerfall or Hammer Fallen which is very annoying when you end up with a loaded chamber in a and a dead trigger because the gun "out ran itself". The echo however has a device called I think the hammer safety device basically functions like a automatic full auto Sear trip in order for that to work what this does is completely eliminate Hammer Falls or Hammer follows what you get the right buffer weight in it and you've also eliminate it won't bounce which is all, did machine gun knowledge here falling M16s you want the echo trigger Because unless you like clearing dead triggers wasting your ammo cuz I wouldn't recommend reloading that Emma once it's been chambered over and over again it's just the echo is the way to go spend the money get a full auto bolt carrier be happy in life and enjoy the f*** out of your gun Life's too short for Hammer follow

        November 15, 2019 8:10 am
    • Commenter Avatar

      The author really gives off very strong Fudd vibes... It almost pisses him off that this thing exists and has to find something to complain about it, bringing up the non-existent laws repeatedly.

      October 4, 2019 10:45 pm
    • Commenter Avatar
      Paul Fries

      Installed BSFlll in an "economy build" 7.5" barreled AR pistol. ( light weight BCG, standard buffer, standard buffer spring) NO issue with trigger. Runs like a "Singer sewing machine". I haven't noticed anyone mentioning how fast the firearm heats up. After a mere 30 rounds even the mag well became uncomfortably hot. Maybe everyone is having too much fun dumping mags to notice. LOL

      September 15, 2019 9:55 am
    • Commenter Avatar

      Thank you for all the information, I have been debating this hole deal about buying a binary trigger. After reading your article it has helped me decide, Like you said I believe it would be better to buy a good trigger system and have a great home defence weapon. Like I always said it's not how many you can shoot and a time, But were they hit the target that really matter. Besides if I want to spray the room I'll use my 12ga with buckshot.

      May 2, 2019 9:53 am
    • Commenter Avatar
      Thomas Payne

      Surrender without compensation? How un-American can you get? How about "Give it to them bullets first"? Who the hell is going to walk away from something they LEGALLY bought only to have government change the rules? Grow a set and remember Lexington & Concord.

      January 25, 2019 1:56 pm
    • Commenter Avatar
      Louis Vaughn

      I put one on a 9mm AR platform SBR, that I built. It's fun to shoot, but I periodically have a problem with the ejection of the second round. It seems that the bolt tends to run a little fast. I'm working on it and hope to fully resolve the problem. The trigger does work reliably in semi auto.

      January 12, 2019 3:23 pm
      • Commenter Avatar

        Use the lighter buffer spring should slow the bcg down a bit

        August 24, 2019 6:09 pm
    • Commenter Avatar
      George Lee

      ” (which I think is probably a good thing, to be honest).
      WoW I assume you vote blue. You probably shouldn't be allowed to own a gun.

      December 1, 2018 4:11 pm
    • Commenter Avatar
      Michael Z. Williamson

      " (which I think is probably a good thing, to be honest)."

      Last sentence of yours I read, or ever will read.

      June 4, 2018 9:04 am
      • Commenter Avatar
        Practical Rifleman

        I read to the end where he said they should be an NFA item so bad people can't get them.
        Never mind the point that if you are a bad person you already can't get the gun.
        But what ever, let's just put everything behind a paywall that only affects legal gun owners.
        Common sense, right?

        July 19, 2018 1:00 pm
      • Commenter Avatar
        George Lee

        A mad man with a AR and bumpstock killed 58 people. A russian woman with a nagant got 528+, which was a more effective weapon. Simo Häyhä had 505 with his.

        December 1, 2018 4:17 pm
    • Commenter Avatar

      I enjoy my straight trigger version. It is definately a full grin ammo eating experience that makes you want to look for another full mag. I have it on a 5.56 pistol with 10" barrel and a Maxim Brace.

      May 31, 2018 4:09 pm
      • Commenter Avatar

        Hello. I have a similar set up. Did you have any issues with Fail-to-feeds, or Fail to Ejects? Did you use the spring that came with the maxim or with the BFSIII?

        January 19, 2021 5:39 am
    • Commenter Avatar

      Um, where are you finding transferable full auto ar15/m16 for $4,000? I really need to know asap so I can buy like 5 of them. Because they haven't sold for those prices in about 20 years. Currently it's difficult to find a transferable one under 20k. Otherwise pretty well written article.

      May 9, 2018 4:44 pm
      • Commenter Avatar

        Matt might have been looking at Dealer Sample prices, those are around $4,000. But ya, a standard NFA full auto M16 is around 20-30k. I'll edit the article a bit!

        May 10, 2018 10:51 am
    • Commenter Avatar
      Rusty Shackelford

      I’m waiting on mine now and had no intentions of buying this prior to the discussion of a ban. It does look like a lot of fun, yet moreover potential prohibition breeds desire. Great write up and I’m looking forward to seeing how much fun the trigger is and how it performs .

      April 4, 2018 6:41 pm
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