The Gas Sub Machine Gun (GSMG)

The GSMG is a gas powered submachine gun that fires .177 or .22 BB pellets.

The gun shoots BBs at 600 fps. If it was able to achieve this with even the heaviest .22 BBs it would only generate just over 12 ft/lbs of energy. Before you get too excited about defending your castle with this legal-to-own-without-paperwork machine gun, it is defiantly not a toy but is not nearly powerful enough for self defense. The GSMG is currently a prototype and the final product will sell for around US$350.

I may be remembering this wrong, but I think after WWII the Allies discovered that a German bicycle-maker had build an air powered submachine gun and planned to use it as an insurgent weapon. More recently an infamous British gun activist designed a air powered submachine for self-defense (he later went to prison for his illegal collection of homemade machine guns).

UPDATE: I was wrong, it was a French bicycle-maker and it was not a submachine gun. See spudfiles comments.

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.


  • spudfiles

    “It is defiantly not a toy, but not nearly powerful enough to hunt with or use for self defense”

    The hunting of small game (rabbits, crows, squirrels, rats etc.) is carried out quite succesfully in the UK with 10-12 ft/lb single shot air rifles out to 50 yards or so, I would imagine that a weapon capable of reasonable accuracy and high rate of fire would be even more effective.

    As to self defence, again it is not ideal but there are plenty of people who have been killed by 12 ft/lb air rifle shots so vital areas, so a mag dump from one of these certainly has potential to be lethal, though of course there are more compact and more powerful solutions.

    As to the WWII airgun, could it be you were referring to the one made by a French bicycle-maker, for use against the Germans, which is in the Beeman Collection?–Austrian-Partisan-Airg.jpg–Austrian-Partisan-Det.jpg

    “Made in the 1940s during WW2, this gun doesn’t look like a Girandoni, but examination shows that it clearly was built by someone familiar with the Girandoni repeating airgun system. Purchased in Europe, the story is that this gun was built somewhere in occupied Europe by a partisan bicycle maker during the Nazi occupation in WW2 . (Originally we suspected that the maker was in Austria but an Austrian friend pointed out that there really wasn’t any resistance movement in Austria – most Austrians still considered Germany and Austria as a single unit, as it had been in the past, and actually welcomed the Nazi troops when they occupied the country, virtually without force.) The repeating magazine is spring fed and on the left side of the barrel, for the convenient use of a right handed shooter. The gun was charged with the accompanying bicycle type pump. Smoothbore, as would be expected, but firing a 11 3/4 mm lead ball (.464″ caliber) (the very same caliber as the original Girandoni Austrian military repeating air rifles!), this would have been a fearsome weapon against sentries, drivers, military leaders, etc. at ranges up to perhaps 100 yards. To a freedom fighter, the lower discharge sound and the lack of flash or smoke would have been huge values. And it did not need powder, primers, or bullets – only easily cast lead or soft-metal balls! The builder surely drew his inspiration from a museum, or even just a book, which displayed a Girandoni system airgun. The excellent quality reflects the experience of a perfectionist bicycle maker with considerable time on his hands – consistent with such a craftsman in an occupied area.

    Note that this gun has a spring fed magazine, rather than the gravity fed magazine of the original Girandoni military air rifle. While a gravity feed mechanism might be simpler, and even more dependable, the spring fed magazine has great advantages for the purposes of this gun. It is more suited for operation from a vehicle or firing slot where it would be impractical to tip up the rifle for loading and it allows firing with minimal motion at the firing point – very important to a sniper.”

    • spudfiles, that must be what I was thinking of!

    • spudfiles, you are right on both counts! I miss calculated the energy of standard hunting breakbarrels 😉 Also that Frenchman story sounds right. Thanks.

  • Ray

    A bicycle pump gun was also experimented with by the SOE but performance was found to be lackluster at best (which is ironic since they condone using flobert 9mm cartridges in their training manual) Also isn’t there a gas powered underwater pistol the Russians have?

  • spudfiles

    No worries, just wanted to clarify 🙂 Also, this is the story of the infamous British gun activist you mentioned, Philip Luty:

    The design for an automatic airgun that was posted on his website was not his but by a certain Jeff Caselman:

    If anyone with machine shop facilities is inclined to build one, complete plans and instructions can be found here:

    • spudfiles, thanks for the info.

  • T

    We’re finishing up a production ready version now… it has actually developed into a much more intense airgun than what is shown in these videos. Sign up for our newsletter to be notified of a release date (email submittal form at this link:

    Thanks for the press Steve,


  • Nick T

    this gun has been in prototype stages for over 5 years now… same with the AJAX bb machine gun, that was supposed to be build with easily obtainable items, run on 100psi air and achieve 1000 fps with several hundred RPM count.

    It’s a pipe dream. In all likelihood, you will never own one. Some guy figured he could make a gun and sell it for cheap and make a ton of money, but has no way to actually produce in such quantities, or do it at such a low cost. This isn’t a company making this, this is one guy, so unless his design gets bought up by a company (it won’t) it’s not happening.

  • anon

    It’s sort of a BAIKAL “DROZD” on steroids. They’re fun, but don’t have much use.

  • Mountainbear

    I remember one of the many, many rumors circling around the death of King Ludwig II of Bavaria was that he was shot with a “Windbüchse” or a similar weapon. Just a rumor of course. It is most likely that he died from a stroke or a heart attack related to the extreme cold of the water when he tried to escape (he had been removed from the throne of Bavaria earlier.) But the murder rumor is still around.

  • Nick

    It’s like a Russian DROZD…

  • spudfiles

    The Drozd uses a solenoid hammer valve to operate, while the GSMG doesn’t require batteries and uses the gas supply itself to cycle the action.

    “It’s a pipe dream. In all likelihood, you will never own one.”

    Nothing wrong with making your own, and it doesn’t have to be complex either. Take a look at this, simply a paintball tank attached to a BB chamber attached to a barrel:

    The results speak for themselves, not bad for air”soft” projectiles even if I say so myself 😉

  • Nick T

    spudfiles, I am well aware of those, however, your comparing buying a Honda (if not a fictional one) to making a skateboard…

    I was on spudfiles for a long time, (sputnick) and while bbmg’s are fun, they are horribly inefficient, inaccurate, and not very powerful. This gun claims a weihrauch barrel shooting pellets, at much higher velocities, with a more controlled valve. Not the same thing at all.

  • .


    I posted it with a YouTube video not mentioned here yet, I believe. Good stuff, thanks… I love follow all the stories here – even these BB-gun ones.


  • Richard K


  • Jason

    You’ll shoot your eye out.

  • Joe

    Knowing very little about the full lineup of fully automatic pneumatic guns, I will pose an ignorant question. Has anybody ever tried to play around with an air gun based on the technology of a shop vac or water aspirator? Essentially I am talking about a modified air ejector. In theory you would be sucking your ammunition into the barrel from the mag although as the BB is accelerated down the barrel you may end up with the same blow back problem as with the GSMG. Maybe that is all the modified sand blaster is…. not sure…

  • Arrkhal

    This is a sorta old one, but what the heck.

    Joe: Your idea is how those incredibly crappy full auto airguns at the county fair work. They just suck up a bunch of lead shot and “squirt” it out the barrel. The shot’s usually ridiculously undersized, and dented all to crap since the fired shot is typically reused over and over. Even with better production values, probably not something practical for anything but wasting people’s money in a midway.

    And a couple of (excessively thought-out) counterpoints for Spudfiles. 10-12 ft-lbs will indeed work fine for small game, but even in a good barrel, there’s a limit to the kind of accuracy you can get from round ball. Now, if the barrel is rifled at an appropriate twist rate, it could certainly be practical with single shots, for any other animal that can be cleanly taken with a single .22 round ball. But the full auto thing adds nothing for hunting. General rule of firing a burst at a human-sized target, further than 50 feet away, is if the first shot misses, the rest will miss–and if the first shot hits, the rest will STILL miss! It takes a LOT of practice to keep an entire burst on target. Airguns might not have very much recoil at all, but it’s probably enough to cause a similar effect shooting at small game, when added to the shock and vibration of the feed mechanism, etc.

    And even if someone does practice enough to keep 3-round bursts in a small group, what’s gained? If the first shot hits a vital area, the animal is cleanly killed, regardless, and now you’ve got 3x as much meat and hide damage. If the first hits somewhere else, the other two will be pretty close behind, so now you’ve got an injured animal with 3 holes in the intestines, or leg, or whatever, instead of 1. I guess that might kill it a little faster, but what’s 6 hours compared to 8 hours, or 2 days compared to 3 days? You’re not going to be any more likely to find the thing and deliver a coup de grace. The chances of your first shot being a bit marginal, and one of the other two hitting a vital area, are really very low, if you think about how small of a burst-group you need, to not be throwing away those other two shots. Anwyay, the end result is, all that practice spent keeping 3-round bursts close together, would’ve been better spent putting 1 shot exactly where you want it!

    For self defense, it still isn’t that practical, given the alternatives. It would sort of be like using shotgun shells filled with broken glass. You intentionally downgrade from something more lethal (like a larger caliber airgun in this case) in order to possibly increase your chances of hitting (I would guess broken glass spreads more than buckshot, anyway), but that also massively increases your chance of collateral damage, and increases the chances that the “bad guy” will survive and kill you, or kill someone else, or sue for pain and distress, etc.

    The same money and/or effort would be better used getting a single-shot, manual action, or semi-auto airgun that packs more punch. One that shoots .45 caliber round balls at 600 fps wouldn’t be too shabby at all. That’s significantly more than what killed Abraham Lincoln, anyway. I’d wager that something like that would be, in practical terms, about as powerful as a .380 at close range. Not great, but way better than a spray of .22 balls at the same velocity.

    So it’s still basically a “toy.” Dangerous enough that many people will yell and gnash their teeth if you call it a “toy,” but still only useful for recreation. And I expect it’ll be very good for that.

  • Matt D.


    I am chomping at the bit to get one of these guns, but have not heard or seen any news on it? When will this be out, and how can I be the first one to get it??????? I currently own a Drozd Blackbird that is fully modded (1200RPM Chip, 23″ Barrel, Clip Magnet, HPA adapter, RIS Rails) I love it but it has flaws. I want this one!!!!!!! Can anyone please tell me where and when I can get one? I don’t care even if it is a prototype.


  • j

    According to the FBI, that could penetrate at least 2 inches into human flesh, probably no penetration if you are wearing a coat or something.

  • Joe Yerace

    When will the gsmg be avalible and where can I buy one? Thank you Joe

  • Bo

    Where can I buy one?

  • glen

    would make a great self defense weapon , who would want to stand there and get shot that many times. you would be bleeding pretty bad and wanting to get help, forgetting about me.

  • Hey There. I discovered your weblog the usage of msn. This is a very well written article. I will be sure to bookmark it and return to learn more of your useful information. Thank you for the post. I will definitely comeback.

  • I have learn some good stuff here. Definitely worth bookmarking for revisiting. I surprise how a lot attempt you set to create this type of excellent informative site.