Engineer’s Delight: Stemple 76/45 Becomes the Stemple Takedown Gun

The saga of how the original Stemple 76/45 became the Stemple Takedown Gun is a fantastic story of engineering design choices.

Essentially, John Stemple began by building a rather crude copy of the Swedish K in .45 ACP in the mid 1980s, called the Stemple 76/45. He produced and registered 2,000 transferrable receivers for the gun (pre-1896), but only built them slowly, a few at a time. In the late 1980s he faced criminal charges from ATF, and transferred the receivers to a friend while he (successfully) fought the charges. When he went to get the receivers back, his friend refused, and the two entered into a nearly decade-long legal battle over them.

By the time Stemple eventually won the case, he recovered about 900 transferrable tubes. By this time (circa 2000) these tube receivers were much more valuable than when he first made them, as the machine gun registry was closed in 1986 and new ones can no longer be made. At this point, Stemple reached out to Brian Poling (BRP Corp) to act as a subcontractor to make the parts for the Stemple 76/45. But Poling had a better idea…

Poling’s thought was to instead design a new gun that would be much more desirable as a recreational gun than the 76/45. He envisioned something controllable, low recoil, and using large drum magazines. Such a gun would be a lot more fun at the range than the MACs and Uzis that tended to dominate the submachine gun market at the time. In addition, Poling’s gun would be designed specifically to protect the irreplaceable registered receiver tubes from wear or damage. The result was the STG-76 – the Stemple Takedown Gun.

In order to remain legal, the STG-76 had to leave the original 76/45 receiver tube cutouts unmodified, so as not to change the configuration of the receiver itself. Poling designed a replaceable internal trunnion and slip-over magazine well, allowing multiple different calibers and magazine configurations. The internals were closely based on the Finnish kp31 Suomi, for which parts kits became readily available in the early 2000s. This also facilitated the use of Suomi 71-round drum magazines. The original STF-76 design also included a bipod for easy shooting, and a grip and stock from an HK91 or CETME Model C for comfortable handling (instead of the terrible metal strut stocks common to most budget SMGs).

Several other interesting configurations would follow (stay tuned for those videos), and the guns remain available brand new to this day from BRP. The original supply of receivers is sufficient for production until about 2023…


  1. Would it be legally and technically viable to change the caliber of this system? A simple blowback would be hard to upscale to a rifle caliber but perhaps a small varmint round, or a .45-.22 conversion, that RIA wildcat or such; or to a 9mm or 10mm or .40 cal? At some point you are replacing or editing parts but where is the line?

    • “Would it be legally and technically viable to change the caliber of this system?”

      Yes, with ATF approval. As noted in the video, Stemple built these receivers for .45ACP, and BRP sells most of them as 9mms.

      Unfortunately, there is no “line”, and no way to get one in the foreseeable future.

      • Except of course for the fact (noted in the video) they did make some minor receiver alterations. So do other popular SMG accessorizers. It’s all up to ATF.

    • “(…)simple blowback would be hard to upscale to a rifle caliber but perhaps a small varmint round, or a .45-.22 conversion, that RIA wildcat or such; or to a 9mm or 10mm or .40 cal? At some point you are replacing or editing parts but where is the line?”
      There is possibility to change caliber without touching any part of gun. Barrel dictates maximal bullet diameter, but smaller bullet could be used in combination with discarding sabot. Remington once produced Accelerator cartridge, which used .22 bullet, sabot and .30-30 case. reports
      .30-30 Winchester Accelerator Express Centerfire Rifle Cartridge, 55-Grain Soft Point Bullet, 3400 fps, 20 Rounds Per Box
      thus as you can deduce this solution allows higher velocity than full-caliber .30-30 bullet (170 grains) , thus hypothetical .22-in-.45 Auto thus providing flatter trajectory thus making distance judgement less vital. Question arise if such ammunition could be developed which would cycle said gun reliably (.30-30 is used mostly in non-automatic weapons).

      • I think you can legally change the barrel; it’s the receiver that’s the “gun” under American law. In my country it’s the barrel (and other pressure-bearing parts.)
        Since the receiver was designed to be a .45″ ACP and ended up a 9mm; you could obviously make it back into a .45″. If you could do it without changing any cuts in the receiver tube, .30″ Luger aka 7.62x21mm might also work, but I suspect that 7.62x25mm or 7.63x25mm (Tokarev and Mauser) would be just too long to feed. If it did fit, though, 7.62mm Tokarev would, though a longish barrel, be as near to a rifle cartridge as this platform is going to support.

        • 7x62x25 is, indeed, offered by BRP. Probably the absolute maximum length limit on the tube.

          Magwells are flexible, but the hole in the tube for the cartridge comin in and the hold for it comin out aren’t. There’ll never be a .357 magnum version, let alone 7.62×39 or .30-30.

          • 7.62x25mm ammunition used to be cheap. That would have been my preference for recreational shooting: flatish trajectory and easier to control in automatic fire. There’s a newer quite powerul 7.5mm pistol cartridge from FN, but it might not fit, might not like a simple blowback action and probably isn’t cheap.

          • “There’s a newer quite powerful 7.5mm pistol cartridge from FN”

            Great idea! It should definitely fit (same OAL as 7.62).

            Blowback could be a challenge, but the open receiver tube creates opportunities. If you add an AR-like buffer tube there, you could not only use a tungsten buffer (or just a longer and heavier bolt), but also allow plenty of free recoil travel to decelerate it.

            You’re definitely right about the price, though, especially in full auto: “Ratatat – mortgage payment! Ratatat – car payment!”

          • “There’ll never be a .357 magnum version, let alone 7.62×39 or .30-30.”
            .357 magnum not, but maybe .357 SIG then? Should fit length-wise, but I am unable to say if pressure it gives will be acceptable

          • Daweo,
            5.7 pressure is very similar, and the P90 gets away with a delaying method that is a very small step above straight blowback.

          • “5.7 pressure is very similar, and the P90 gets away with a delaying method that is a very small step above straight blowback.”
   states is a blowback operated. Guess difference caused by using different classification. Anyway, 5,7 x 28 mm cartridge was designed from onset for such usage, whilst 7,5 FK was not. Further inquiry would be needed to determine if case construction is fit for usage in blow-back operated weapon which modification is limited due to legal reasons.

          • Daweo,
            Good point. In terms of safety, any cartridge can be safely used in a blowback as long as the bolt mass provides sufficient delay. In rifle cartridges this is limited in practicality by size, recoil, springs that a human can compress, etc. The 7.5 is energetic, but also uses light bullets, so its bolt shouldn’t have to be impractically large.

            On the other hand, I doubt it would be popular with reloaders.

  2. From ‘close friend to nemesis to business partner’… gimme a break 🙂

    Who does not understand this, does not know America (and I mean whole norther part from Rio Grande up). All a matter of convenience/ inconvenience. Sad? NO, amusing.

  3. Holy narrow niche market Batman!
    Just goes to show that no matter how you write regulations, some one will always find a way to circumvent those regulations.

    • Where is circumvent? My understanding that quantity of transferable guns was hard capped and could not be increased. I guess that U.S. system regarding transferable-ity is way too complicated for me.

      • Daweo,
        Your understanding is completely correct. The market is niche, but extremely profitable: these would have cost Mr. Stemple less than $100 to make; BRP adds a few hundred dollars worth of parts and sells them in the tens of thousands today.

    • Regulations were not circumvented. That’s the (not quite) whole message of the video. The genius was that the design was in complete compliance with the regulations. If ATF is happy then everyone is happy.

      • “If ATF is happy then everyone is happy.”
        Ummm… No.
        Appeasing the whims of an over-reaching bureaucracy run by a politically motivated functionary is not my idea of happiness.

  4. Strange thing: I made eight attempts to view this video through the normal YouTube site, and it crashed the windows 7 laptop I’m using while my Linux machine is sick, every time. (It’s running Firefox rather than Googel Chrome). I think this may be a tracker connected with the adverts?

    But using the same machine I viewed the same video here first go with no problems, even though it’s 28 minutes long!

    Either Gun Jesus has worked a miracle (bless you, Ian), or there’s something on You Tube that’s conveniently (for Google) incompatible with a non-google browser. I may make a habit of viewing videos here!

    • I only watch FW here, unless it’s something Mr. M. forgot to post or only uploaded to YT. Higher quality and informativeness of commentary, too. Welcome aboard.

    • “(…)eight attempts(…)”
      Once is happenstance. Twice is coincidence. Three times is enemy action (Auric Goldfinger)
      Anyway if you encounter similar problem in future, you might try to download youtube video (search for youtube downloader or similar) and after it end watch it using video player.

      • I will look into that.
        Interestingly, the last site youtube tries to connect me to, before it crashes, is “CurrysPC” ie: Currys PC World, a computer retailer in the UK. So I’m supposed to buy a new computer! Deliberately stopping my old computer from working is actually a crime under English law.

    • “crashed the windows 7 laptop…”
      No way! Get yourself Windows 10 and Chrome and you will be fine. Mine never crashes.

    • Using Windows 7 for accessing the internet, a Windows which has been no longer supplied with security patches for quite some time, is the IT equivalent of smoking while handling gunpowder. Sorry for being blunt. In my opinion, after more than three decades in this field, its not “something on You Tube”, but simply something on your effectively unprotected Windows 7 PC.

  5. Actually, this would do well in WWII. Germans would be thrown off with its appearance; they’d think Muricans copied MG42. Time machine… quickly! 🙂

  6. Remember seeing one of these for sale a while back, and thought it had been intentionally designed to be modular, to allow various configurations all via one receiver.

  7. I’ve got an earlier version of the STG. It’s very similar to yours in the video but is not marked BRP. Has an extra lug under the barrel jacket with a screw in the end. Unthread it and the barrel sleeve comes off and the barrel comes out. The barrel isn’t pinned in like your example.

  8. Making and registering all those tubes just prior to the tyranny of 1986 was a genius level move on the part of Mr. Stemple. Considering I was 14 years old in 1986, I must once again point out that I hate everyone that had anything to do with the Hughes amendment, as I possess all of the tools and knowledge to manufacture all kinds of fun toys. I have everything but the permission slip, and it chaps my behind.

    • Don’t look at the prices of real M16’s then. MAC’s and STEN’s were starting at the 6k$ range and that was a few years ago. The prices are so high since no new civilian transferable MG’s can be legally made. All because some rich guy in NJ who constantly spewed the “I’m a sportsman” line wanted it that way.

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