If Frankenstein was a 9mm Bullpup

This frankengun cost its builder just $100 in parts. The stock is part steel and part polymer from a H&K SL8 rifle, the recoil spring is from an FAL, the bolt and barrel are from a Sten submachine gun. Why are no major manufacturers making a badass gun like this?

*[ Many thanks to Chris for the tip. ]*

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Sivispace

    Well, time for you to start manufacturing them. With a threaded barrel please.

    • Layden

      Looks like something FPS RUSSIA will copy and call “revolutionary” with a statement like “I thought of this in the gulag” or something

    • Layden

      Looks like something FPS RUSSIA will copy and call “revolutionary” with a statement like “I thought of this in the gulag” or something.

  • Reverend Clint

    call red jackass and get that beast in production

    • El Duderino

      “We’re looking to move into a new market with this one.” — Will Hayden

      • gunslinger

        “It’s a GAME CHANGER!!!!” “This is something that hasn’t been done before.”

        and on…

  • Doug

    That’s awesome. I want one.

  • Kommac

    Left handed shooters beware, you WILL get your teeth knocked out by this one.

    • El Duderino

      Uh yeah, reciprocating charging handle where the face goes. No different than those bullpup AKs though.

    • Burst

      With this level of customization, though, it’s not such an issue. Make the cuts in the other side, flip parts as needed.

      • Burst

        reversing the Sten gun parts might be a bit trickier, I guess.

  • So those are Sten magazines then?

  • Jefe

    That thing is pretty damned cool. Especially on that budget. Somebody needs to do a range report.

  • BenJamin

    I’m not big into the pistol carbines, but I’ll definately make an exception for this

  • W

    Extremely desirable for:

    1.) Gun owners looking for something neat to shoot.

    2.) Sci-Fi studio Armorers looking to equip their space marines for a functioning prop πŸ˜€

  • D.Moura

    If you have contact with whoever did this, ask for a demonstration video!

  • Sian

    Looks like something from Tediore.

    I like it.

    • Clodboy

      Yeah, definitely something straight from the Borderlands universe πŸ˜€ … or something created with that “Pimp my Gun” flash game.

      On a more serious note, am I the only one who really likes the look of the SL8 thumbhole stock? Sure, people hated it because it was no G36, I always thought it was a pretty slick piece of German aesthetics.

  • David/Sharpie

    I want, but with a longer barrel so it’s Non-Restricted in Canada.

    And for less than $500…

  • RocketScientist

    Where did this come from? If there’s a build thread on a forum somewhere I’d love to read it. Or was it a reader submission?

  • Very cool looking build… i would love to see more information on this build, and I think my members would love to see it as well.

    one other comment… that last thing I expected to find on the firearms blog was a picture of me at the top with my L1A1

  • Steve Day

    I just performed some GoogleFu and found where the builder posted about his creation:

    • RocketScientist

      Thanks! Good find!

    • Doug

      Great find. It wasn’t until the end of the thread that I realized this was made in 2010. Hopefully it’s a lot closer to production fruition now.

    • Matrix3692

      this is the type of creativity that should be supported, hope the guy succeeded in making more guns in the future(including the .45 and 7.62×25 variant of this gun that he mentioned).

    • noob

      oh the missed opportunity to name this tfb article the “FrankenSTEN”

  • Darkness

    I like… Can I has?

  • Matrix3692

    I am absolutely love in first sight with bull-pup type weapons, and this gun is almost my dream gun. Now I’m thinking of a gun design with longer barrel, four column casket magazine, and a “not yet decided” recoil reduction mechanism…..

  • Billphoto

    Great idea! I would enjoy seeing more info on this build.

  • Franky

    that is a sexy beast. i would love to manufacture my own.
    a few modifications that i would make:
    first off, i think the handguard should be a rail system, maybe reach down a little further, so accessories can be added as needed.
    there should be an iron front sight, possibly foldable, that would be nice. the charging handle looks a bit awkward, maybe change it to a simpler design, or perhaps run it up front and ambidextrous like the ACR or SCAR platforms

    other than that, i think there needs to be a parts kit on the market for this gorgeous device.

  • bbmg

    “Why are no major manufacturers making a badass gun like this?”

    Does the Jianshe Industries (Group) Corporation count?


    • Doug

      No, because we can’t have it. πŸ™‚ My computer blocked a virus from the link you provided.

      • Matrix3692

        it’s a link to a article about the chinese type-05 SMG (a.k.a. JS-05), many chinese sites are blocked because of the same problem, probably because the amount of pop-up ads in those sites…… although it has a similar appearance, the type-05’s parts are manufactured for it, not the ‘Frankenstein’ style parts from other guns.

      • Matrix3692

        sorry, correction: JS-9, not JS-05

      • bbmg

        Hmmm… no such warnings on my end, either my anti-virus is very permissive, or the Chinese site doesn’t like stateside ISPs.

        Here’s a Russian based link, we’re meant to be allies now πŸ˜‰


      • bbmg

        “although it has a similar appearance, the type-05β€²s parts are manufactured for it, not the β€˜Frankenstein’ style parts from other guns”

        That was the point of my original reply, there *is* a major manufacturer making a gun of similar configuration and performance to this prototype.

      • W

        google chrome baby. ditch that wussy IE9 πŸ˜€

    • Denny

      Hmmm, this is QBZ based, isn’t it? Yeah, it would count too, albeit bit phunny looking. Pardon me my engrich!

      • bbmg

        Aesthetically the QBZ does have a very similar configuration, but I would be surprised if there was any parts commonality.

      • Denny

        I know bb, its just the same housing. Do you know, if they sell this SMG at civilian market, as a carbine? I know, there is or will be QBZ rifle on sale in Canada.

  • Big Daddy

    This looks a lot better than those pictures of home made machine guns. I bet this one can also be full auto very easily.

    I wonder how it shoots.

    Gotta give credit to a guy who can make something like this, very cool and it looks great too.

    • Big Daddy

      Just read his post and he says it is full auto. Seems like lots of fun.

    • David/Sharpie

      Is handmade full auto legal? For your personal use I mean.

      Forgive my ignorance, I’m Canadian, although I know most of your federal laws.

      • AC

        If he’s making it from sten parts, it probably doesn’t count as making a new weapon any more than putting a 22lr (or other cartridge) conversion kit or a different stock on an AR-15 does.

  • Jaymes

    Me want. Enough said.

  • Tinkerer

    That is an incredibly cool firearm. I feel it fits the spot nicely for home defense/backpack gun -unless you live in Bear Country-.

    I wonder… It seems that the bolt’s recoil travel is over twice as long as the lenght of a 9mm cartridge. Considering that, wouldn’t it be possible to move the ejection port back and turn it 90ΒΊ downwards, so the spent cases would be ejected downwards behind the magwell? Somehow like the P90 or the old S&W M1940 light rifle? That would do wonders for that bullpup’s ambidextrous capabilites. That, and a wrap-around bolt with forward charging handle.

  • John Doe

    He says he’s going to make one in 7.62x25mm as well. This guy is just awesome.

  • shenji


  • Bryan S.

    Great, unless you live in the US with the NFA and GCA. Making a full auto gun is pretty cheap, its the mechanics to do a delayed blowback semi-auto that cannot be easily converted that gets it complicated.

    • Actually, there were some Class II manufacturers who had squirreled away pre-’86 Registered Receivers for making Sten SMG. The Stemple 76/45 receivers might also work. BRP Corp. has used the latter as the basis for several transferable conversions like their Soumi look-alikes.

  • Hikerguy

    No two ways about it: AWESOME!

  • Steve

    I bet that thing points extremely well. I find that very desirable in a 9mm carbine. I’d pony up for something like that in a heart beat if you could transition to a more dependable and easily found magazine.

  • mechamaster

    Uhh.. if they made it rapid-fire version enable, I recommended to add kevlar cheek plate in countermeasure againts KABOOM Incident in right of user face.

  • gunslinger

    that’s a neat little gun. how is weight for a PDW? anything other than 9mm?

    still i think it’d be fun to shoot.

  • alannon

    I’ll admit that I some some areas I would alter. Non-recip bolt, downward ejection, something about the front end to make it better match the aesthetic of the rest.

    Those alterations fail utterly to detract from the awesomeness of this project. I mean, I never would have even thought to pull parts from such different guns to create a functional firearm. To say nothing of one that looks pretty badass as is, and with a full manufacturing shop behind it would look awesome.

    Props to the guy that did it.

  • tincankilla

    the original post was over 2 years ago and the builder said he was going into the firearm biz – any chance of an update?

  • Michael

    Looks like a great PDW/home defense weapon
    Like the idea of 7.62×25

  • Andy from West Haven

    Have any of you ever tried shooting an SL-8? Or even held one as if you were going to shoot it?

    That “thumbhole” was designed for 8 year old children with some bizarre form of arthritis. It is literally uncomfortable to hold and if I tell my hand to grip it like I would anything else it’s borderline painful to do so.

    Just look at the interior of the thumbhole. Does it look nice and rounded? Does it look ergonomic? I’m talking about where the web of your thumb meets the stock. Okay fine. It’s polymer. You could smooth it out to an extent. But why should you have to?

    The SL-8 is HK’s worst loogie they could ever spit in the eye of the “civilian” shooter.

    Yes, this gun looks interesting and I applaude the person for making it but I find it amusing that so many are jizzing in their pants over this and they never experienced SL-8 face. Which is the face you make when you first try putting your thumb in that stock.

    • Big Daddy

      You are correct but miss the point. The point is he made something that nobody here can. He built a weapon with leftover junk that shoots and probably shoots well, not a precision rifle, a fun gun.

      If I shot it I probably would not use the normal grip and leave my thumb out to the side. Although probably incorrect I have seen people many years ago fire lever action and bolt action rifles this way. I am guessing they do so to increase the speed of their next shot as they do not need to shift the position of their hand to chamber another round.

      Getting back to this gun. A guy took some junk and built an operational weapon that looks great. I cannot do that and I admire anybody that can do things that well and from junk. This guy has a lot of talent. I sure would rather watch a program of him building weapons than Red Jacket.

      • Andy from West Haven

        Are there videos of this gun being shot? How can you say, “it probably shoots well.”?

        This guy isn’t a game changer. He’s not the first to build a gun from junk. And as far as the stock, you do not deny that it’s awful but are willing to bypass that fact by shooting it with your thumb alongside the gun instead of through the stock as intended. That’s like Steve Jobs telling you that you won’t lose reception on their phone if you hold it a certain way.

        Regardless I said in my first post, “this gun looks interesting and I applaude the person for making it…” so I did not miss the point.

        It’s the stock I have the most issue with. And the fact that people go absolutely nuts when they see something they’ve not yet encountered and willing to forgive anything and everything that might be wrong with it because ZOMG! THAT’S SO COOL!!!! So what if the stock and the Sten mags totally suck! TAKE MY MONEY!!!!!!!

      • T.

        Made something nobody else can? I can think of three people off the top of my head that I know personally that could make a gun from scratch.

        Neat, sure. But it’s not rocket surgery.

      • Clodboy

        “I sure would rather watch a program of him building weapons than Red Jacket”

        If the theme was WW2 mags, Red Jacket would probably mount an upside-down Bren machine gun on the bottom rail of some hick sherriff’s 9mm AR-15 carbine so he can provide heavy fire support when arresting oxyheads. πŸ˜‰

    • Big Daddy

      There is exactly one or two people where I live that can make a gun from junk. The total population of my place of residence is 450,000 people. The size of the Island I live in 8 miles by 12 miles, yes with almost half a million people living on it.

      The simple fact that it did not blow up in the guy’s face and that he is going into business building guns leads me to the logical assumption that it probably shoots pretty well. For a sub-machine gun that doesn’t mean a whole lot as they are inherently inaccurate. I know, I carried a M-3 grease gun while in service.

      So yes I am impressed because I do not even know someone who could build that. I know in time I can figure it out very easily as many people can and with those parts make a functional weapon. But right now, no I cannot.

      Now if you are talking about cars, race cars and many other much more complex things yes I know many people that can and have built them. I myself can build Guitars and guitar amplifiers and have sold them, working custom designed ones.

      So I am a builder and know others that can build amazing things.

      But as far as weapons like this in my congested area in New York Sheetty no. People never consider that other people live in areas that have completely different demographics. That seems to be a huge problem these days.

    • Sian

      This is probably why SL8 thumbhole stocks like this are in wide and cheap supply.

      Anyone with a real SL8 has already re-stocked it and added a G-36 magwell for proper double-stack mags.

  • claymore

    Well I can see from the comments that most people here have never had much time behind a Sten gun. Those Sten mags and Sten parts are JUNK and you see that little lever on the top of the mag in most photos?

    That MANDATORY little lever is the “loading Helper”. Since it’s a single column mag one can NOT load by hand unless you have “superman fingers” at least or that tool and if it goes missing you are SOL.

    Loading times are horrendous to say the least.

    But you will be needing it frequently because the mags are so terrible EVEN BRAND NEW (if you can find one) you will need to bring a bunch of loaded mags to keep it fed and yes even in semi auto.

    If you see a firearm that uses Sten mags turn quickly away and run or you may pyrchase one and be sorry.

    • Clodboy

      By the end of the war, the Germans got so desperate that they started sending in old men and teenage boys into war as part of the Volkssturm. They also got so desperate that they designed a clone of the British Sten (a gun they had captured in large numbers during the years before, but regarded as too primitive for their own forces to utilize), the MP3008, to arm them with on the cheap.
      They still wouldn’t lower themselves to use Sten mags though, and designed it to utilize those of the MP40.

      Anyway, I doubt the users here are necessarily asking for a gun that uses mags designed for a crappy WW2 gun – just a cheap, cool-looking bullpup pistol-caliber carbine capable of utilizing high-cap SMG mags.

      • Anon. E Maus

        It’s the same magazine, you fool.

    • Son Of Plug

      Last time I checked the sten gun was designed to use MP40 mags as well so there’s always that.

  • Denny

    Admirable undertaking, spectacular result! Just one small thing to mention – the Sten was not the best subgun in terms of relyability (it was war time product after all); Sterling upped them quite a bit. But, I realize we talk a ‘hobbyist item’, not an issue weapon. All the praise to the creator!

  • Hami

    Because of the SL8 to G36 conversions those handguards and especially the thumbhole stocks are a dime a dozen. I have one at home i would have eventually trashed one day. Now i see a reason to hold on to it!

    • Clodboy

      Thanks, I was actually wondering how he got those SL-8 parts so cheap.

  • Mike Knox

    A 9mm in a rifle stock, I may have seeon one before. If this goes on the market, IMI might have a lawsuit about this and their 9mm MTAR-21.

    This reminds me of my 9mm garage gun I made in high school..

  • Lance

    I like it nice P.C.C. But Id prefer a SL-8 change to a G-36 over a 9mm carbine.

  • Was this in Killzone?

  • John Doe

    A man makes a futuristic, fully automatic bullpup submachine gun himself. How effective do dumb gun laws sound now?

  • mosinman

    oohhh… i like that…. (frito from the movie idiocracy)
    good work on the gun though, gunna have to build my own someday

  • Brutalist Archetype

    I think that would look awesome with a calico helical feed drum instead of the stick.

  • Charlie

    So what is he retailing the kit for?????

  • NI Shooter

    How the heck did Frankenstien get a 9mm bullpup in himself? Oh, did you mean if? πŸ˜‰

  • Mark

    The only thing I’d change is to have this with a helical magazine. Then, the next thing I would proceed to do is throw oodles of currency at this design to own one.

    • Mike

      I’m trying to imagine a bullpup Calico type of thing here.
      It’s a bit hard. But I believe it’d work. Sure, you’d have to hack a lot out of the stock, and end up with something straight out of the Killzone series, but with some design tweaks it’d be pretty cool.

  • A very creative and cool looking design. Aside from that though, for all practical purposes this thing looks like an ergonomic nightmare. The gun just looks “clumsy”, for lack of a better word. I wonder what the weight balance is like, and if it is top heavy or muzzle heavy. Don’t get me wrong, it’s definitely cool, but I wonder if looks is all this thing has going for it (not that there’s necessarily anything wrong with that).

    • Isaac

      I would gladly buy three of them, at $150 a pop. He’s gotta make a profit, after all. πŸ™‚

  • Exoticbirdhunter

    Put a P90 mag on top and chamber it in 40 S&W and they’ll be beating a path to your door

  • average american

    Looks promising, put some rails on it, a verticle grip on the front, a threaded barrel end so you could use a suppressor

    modify it so it could take glock 33 round mags instead of sten.
    and you have a nice urban close quarters weapon.

  • Anon Builder

    Just going to say the guy who made this is a crook. He stole thousands of dollars in equipment and firearms parts among other items from other builders on a forum.


    • Nick

      Could you elaborate on that a little bit more? I was wondering how he got all the other parts so cheaply. LIke the muzzlebrake and foregrip.

  • Rhino

    Show me a video that it works.

  • camosoul

    I’m working on something similar for a DIY “negative zero percent receiver” kit OMG GHOST GUN!!!