Bullpup AR Conversion

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Recently I stumbled upon this gem of creativity, a fellow somewhere in the US who designed and put together a bullpup configuration of an AR15 by re-configuring the trigger group into a stock, putting a pistol grip and trigger guard along the rail system, raising the EoTech by about 2 inches with a rail riser and then adding a tube above the buffer tube to form a cheek weld while still keeping the charging handle in the original location. We’ve blogged about various AR bullpup experiments before on TFB, one that only had a trigger bar mounted to a grip on the forward rail, and another one even more extensively modified than this one, in completely redesigning the lower receiver to accommodate the upper receiver. However this design seems to be much more compatible with drop in parts to the parts that this guy came up with. He has also done the exact same thing to an ARAK upper receiver, which of course can work with an AR lower as it is. So far it seems that this fellow has just done it the one time in 2014, and hasn’t shown any subsequent modifications since that time. It would be interesting to see if this idea ever takes off in the future, sort of how similar ideas are applied to AK and M14 bullpup drop ins.

I built one. The JMT lower is a plastic lower made to look like a billet rather than a mill-spec. There are no alterations to the lower. I used a short pistol buffer system. It measures 28.5 inches without the compensator. It has about a 4 pound trigger pull since it started with a 3.5 pound Timney trigger assembly and my pull bar remote trigger adds little if any resistance. I have a trigger scale coming so I will know more later. No I can’t and will not make any of these parts for anybody save your breath. It took way too much time and energy for what the results are. They aren’t bad it is fun to shoot but the cost is nearly the same as buying a Tavor.

I use a rod in a tube. The rod is pulled. There are slots in the tube for arms to engage the rod. The arms engage slots in the rod. You can see the tube running from the front grip trigger assembly. The rear lever pivots on an extended front trigger pin. Both levers use the same length levers so the trigger pull is the same as it was to start with except for a tiny increase in friction which honestly isn’t noticeable but I won’t argue is not there. The front trigger pivot bar pivots in ball bearings.

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Miles V

Former Infantry Marine, and currently studying at Indiana University. I’ve written for Small Arms Review and Small Arms Defense Journal, and have had a teenie tiny photo that appeared in GQ. Specifically, I’m very interested in small arms history, development, and Military/LE usage within the Middle East, and Central Asia.

If you want to reach out, let me know about an error I’ve made, something I can add to the post, or just talk guns and how much Grunts love naps, hit me up at miles@tfb.tv


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  • st4

    Reminds me of that Killzone rifle.

    • John

      I really, really wish the Helghast version had their own sight on top. It’d even be a red dot.

    • lucusloc

      Bah, I am too much of a gun nerd to like faked weapons like this. I see too many of the incorrect engineering details to think the artists did a good job. They copied the AR upper and lower mating without paying attention to the why of that mating for example. How do those two pieces come apart, when the barrel needs to pass through the rear of the part all the way to the bolt face? Why is there a metal heat shield over the top rail? How does the bolt fit into that small space at the rear, and still cycle a cartridge? Are there any other controls other than a trigger? I don’t see enough space over the barrel for a gas tube or piston, so it must be below the barrel. With that assumption, why is the charging handle on top? Where is the bakup rear sight?

      And don’t tell me “rule of cool”; correct engineering is cool dammit. Faking it means you just did not care enough to get it right.

      And yes, I also ruin movies. It is a curse.

      • Blake Allen

        It could actually work. The Russians built a few bullpups with U shaped bolts, allowing for the magazine to be just an a few short inches from the buttpad. Looking at this rifle, if the barrel extended all the way to the end of the AR styel upper, it could be possible. If the bolt were telescoped like the uzi, than the AR charging handle could possibly work. As for the heat shield, that is an odd place for one. Based on how it look, it wouldn’t work. But, with a few modification (a slightly enlarged bolt section) it could feasibly work.

        • lucusloc

          Yeah, a few tweaks could make it right. That’s the part about me that bothers everyone else: they see a cool gun, I see problems. Then I teach them a bit, and they see problems too. Now the curse has spread. It like lycanthropy, only instead of howling at the moon, we howl at prop departments and animation studios. . .

          • DIR911911 .

            that’s how someone eventually gets inspired enough to go to hollywood and get it right. . . you are planting the seeds of dreams 🙂

          • lucusloc

            Go my lycanthropic friend, show me things of beauty.

          • iksnilol

            All right!

            You wanna know my political persuasion?
            Well, sugar, I howl at the moon

      • st4

        I think the right way to do it is to part together something of existing, functional weapons like old Hollywood, then make-up whatever post-processing you want. My favorite examples being the Pulse Rifle from Aliens and Robocop’s Auto-9 (and Cobra Assault Cannon). Alas, not many game studios are willing to do that when they can go straight to 3d asset after some concept artist, no doubt unfamiliar with firearms, kludged a few things together from a Google search.

        • lucusloc

          Yeah, only you have to understand the subject matter to put it together right, otherwise you get crap like this. The individual parts are right, and done very well to boot, but taken as a whole it is all wrong. This does not bother me nearly as much in funny, over the top games. For example I buy into the boarderlands universe, weapons insanity included, because it is not supposed to make physical sense. And then you have the portal turret (65% more bullet per bullet!) taht makes me laugh every time. The insanity is purposeful and with style. I can get that.

          But when a supposedly “lifelike” movie or game (that supposedly spent tons) gets it wrong? Dude, just hire a real gun guy to come in and set your artists straight. Hell, if you feed us I but most of us would do the job for free. . .

          • Out of the Blue

            The portal turrets, in fairness, are supposed to be illogical in design. Almost everything about Aperture is. The developer notes for Portal 2, in fact, detail that they used a pneumatic tube delivery system because they thought it to be the least efficient way to deliver stuff throughout the facility. It’s still inaccurate but the sin is deliberate in that case.

      • Joe

        You and I would get along great! I too am a gun snob and cant stand fake gun crap. Plus I ruin movies too.

        • lucusloc

          The few, the cursed, the proud. Become a Gun Snob today! 🙂 (May void friendships and relationships. Viewer discretion is advised, but unlikely to happen.)

      • Arashi

        What are you talking about?

        The last version is the ARAK 21 upper that has no buffer tube.

        Correct interpretation of the presented imagery is the “rule of cool”.

        • lucusloc

          What has been seen cannot be unseen. There is no more “rule of cool” for me. Only the rule of “no, that is not right, this artist doesn’t know anything about the subject material. . . “

      • DIR911911 .

        YES 🙂

      • n0truscotsman

        http://vignette1.wikia.nocookie.net/halo/images/9/9c/MA5B.jpg/revision/latest?cb=20070121152826

        There’s apparently 60 rounds of 7.62x51mm in there somewhere…

        • Paladin

          What I find even more odd than that is the UNSC still using 7.62×51 in the 26th century, you’d think that with 500 years to work on it they’d be able to come up with something better. Maybe we should follow their lead and start suiting the guys on the pointy end of the stick in plate mail.

          • n0truscotsman

            I would have to guess that with a colonial military force that large, they would be strapped for money for far more pressing concerns, like ships and orbital defense platforms (i assume they have those, every sci-fi franchise does).

            7.62×51 is a very odd choice. Especially, per the wiki discription, if it has *poor dispersal* and a *high rate of fire*. 0__o

            But exploring further, I do love the idea of a semi-automatic 14.5mm sniper rifle. Why fix whats broken I suppose?

  • BattleshipGrey

    Very strange, but just this morning I was wondering if there have been any recent attempts at making a bullpup from an AR. Thanks for posting this.

  • Sianmink

    The length of pull looks kind of ridiculous on the standard upper version, never mind T-handle follies. The ARAK design looks better put together (Helps it doesn’t need a buffer tube)

  • Dracon1201

    It is like Frankenstein’s monster! Beautiful in its own way.

    • lucusloc

      100% agree.

  • Lance

    Good way to tacti cool screw up a good AR.

    • Vitsaus

      As opposed to all the tacti-kool aid people have been drinking for the last 10 years over the AR 15 platform?

    • Kelly Jackson

      It’s $50 80% lower

      If $50 is going to make or break you then you’re probably in the wrong hobby

  • Drapetomanius

    I try not to decry projects like this. Yes, it’s probably over priced, hideous and impractical; but not every project has to have the ultimate aim of creating marketable or practical goods. Some projects are just an exercise in thinking around an arbitrary problem, to see if you can. I salute the tinkerer’s ethic.

    • lucusloc

      Yeah, I cannot wait to get my home shop up and running. I’d ,make abominations all day 🙂

  • They finally did it…

  • TechnoTriticale

    Isn’t this how Bushmaster originally got into business?

    Yeah, I know, it was a sort-of Colt IMP (GUU-4/P) clone, with really terrible sights.

  • C.

    Didn’t the guy from Demolition Ranch also make a bull pup AR?

  • K R

    Just buy a Tavor.

    • Blue Centurion

      This

  • me ohmy

    ..

    • iksnilol

  • noob

    I like this. I wanted to make a much uglier one I’d call the “AR-bomination” which would use the lower as an extraneous part decoratively affixed to the bullpup stock as a joke. This actually respects the mechanics of the lower. I am surprised that retaining the buffer tube didn’t make the length of pull overly long. I wonder if a pistol buffer and pistol barrel could make an even shorter bullpup with mostly compatible ar15 parts as a full-house all-metal carbine caliber powered PDW, but with fewer parts than a Tavor.

  • Dan Atwater

    This is just too cool

  • HenryV

    Lovely. Well done that man. 🙂

  • Bigbigpoopi

    If it matches the K&M’s trigger pull I’m interested.

  • iowaclass

    It’s really surprising that there is no commercially viable bullpup AR conversion.

  • Blue Centurion

    What a waste of a perfectly fine rifle.