The K4 compact subgun project from Argentina

The family of very compact submachine guns that came from the creative mind of Gordon B. Ingram starting in the mid-1960s and subsequently series manufactured in the U.S. by the Military Armament Corporation (the .45ACP M10) and the SWD company (the 9x19mm Cobray M11) in the 1970-80 period or so may not have become true operational winners, but their general conceptual idea (“firepower in a very compact  package”) did call the public  –if not LE and military –attention. As you sure know, this resulted in a large number of close copies appearing in different parts of the world, South America included.

In a recent post here in TFB (, I was able to share info and pics of a little known Brazilian design dating from 1985. Now, it’s time to show you a totally unknown compact subgun project that emerged in Argentina three years later. The idea came from a local designer called Antonio Ureña, who reportedly worked for the country’s Policia Federal (Federal Police), final plans of which emerged in January, 1988 after some years of laborious in-house studies.  Designated the K4, it was a simple 9x19mm open-bolt, blowback-operated selective-fire weapon employing Browning Hi-Power-type magazines of 13- and 36-round capacity. This was certainly a result of that pistol being locally produced by State-owned Fabricaciones Militares for any years.

Compactness of Antonio Ureña’s K4 submachine gun can be clearly seen in the side-by-side comparative drawings with a Browning Hi-Power pistol. This has been manufactured in Argentina as the FM M95 by Fabricaciones Militares for many years.

The main body was a rectangular stamped steel structure, the similar-shaped receiver cover being hinged up to give access to the firing mechanism, bolt and recoil spring so as to allow basic maintenance procedures. Synthetic components were used in the pistol grip/magazine housing area, as well as in the very large trigger guard, which was also given the task of providing some support for the non-firing hand. The fire selector was a sideways-moving button (“AUTO”, “SIMPLE”) just above the trigger, while the applied safety lever (“SEGURO”, “FUEGO”) was located slightly ahead, on both sides. A grip-type safety lever was also incorporated. The cocking piece was on top, and the ejection window, to the right. This was provided with a manually-operated dust cover, which automatically opened when the gun was cocked. Another feature was a retractable, wire-type buttstock.

The weapon with the receiver cover swung open to give access to all the firing components.

A dedicated (K4S) sound suppressor was envisaged, this having its own 207 mm integral barrel and being 227mm long and with a 67mm diameter. It would be attached to the gun’s front mounting collar after removing the original barrel. To my knowledge, the K4 never turned into a real prototype hardware, but maybe Argentine readers might throw some light on that.

Cross-section drawing of the Argentine compact buzzun design.

“Proyecto UR – Pistola Ametralladora K4” – BASIC DATA:

Barrel length: 182mm (6 grooves, RH, 1:380mm); gun length, no stock: 310mm; gun length, closed stock: 325mm; gun length, open stock: 470mm; gun max width, 45mm; height, no magazine: 160mm; height, with 36-round magazine, 277mm; empty weight:  2.3kg.

Ronaldo Olive

Ronaldo is a long-time (starting in the 1960s) Brazilian writer on aviation, military, LE, and gun subjects, with articles published in local and international (UK, Switzerland, and U.S.) periodicals. His vast experience has made him a frequent guest lecturer and instructor in Brazil’s armed and police forces.


  • Anonymoose

    I want an SMG that takes Hi-Power mags. Forget the Glock mag blocks, gibe Hi-Power pls!

    • Joshua

      I have been thinking this for ages, I want to get into designing guns, and I love the Hi-powers ergonomics, and since it’s standard service sidearm where I am they are fairly plentiful and (comparatively) cheap, why not use their mags?

      • Anonymoose

        Wait, you aren’t the same as the Special Forces Joshua, are you? Where are Hi-Powers still the standard? Belgium?

        • Joshua

          Canada, actually SF here carry Sigs if I recall correctly, but standard line infantry still carry HPs, most commonwealth countries still have them as standard, and I believe most of Africa as well. They really are the 9mm equivalent of the 1911, they might be a little behind the times, but everybody loves them and they still accomplish the mission.

  • Stuki Moi

    Can anyone explain to me why something like this, with tracers, would not be about as good a bear repellent as can be practically carried into any bush anywhere?

    Never shot an Ingram gun, but a similar capacity MP5 has apparently been scientifically designed to deliver all it’s payload in exactly the amount of time it takes between a bear charge in process becomes apparent, and it turns fatal. The Ingrams are smaller, yet still plenty shootable and accurate for the very upclose and personal affair that is a bear attack.

    So again, why not one of those, instead of loud, cumbersome, shoulder dislocating lever guns?

    • Joshua

      having seen video of people shooting a mac-10 style gun, I would be very impressed if your average backwoods goer could dump a full mag into a bear sized target, also, depending on the bear and ammo, 9mm is not sufficient in power or penetration to put down a big angry brown, and while 36 9mms may be enough to convince it to bugger off, one or two .44 mags will put it down.

      combine that with ease of carry, even a big bore revolver is smaller and lighter than most machine pistols, machine pistols are notoriously unreliable, and in Canada and United States, are mostly illegal, and so are tracers, also, why would you use tracers in this application? are you trying to set the bear on fire?

      • roguetechie

        Tracers are far from illegal here in the states.

        I just recently finished a sexed up semiautomatic only build of the chichizola MPA with the magazine forward of the grip in 7.62×25 using Czech cz-26 magazines.

        I can safely say that it would not only kill a bear dead as hell with a full auto mag dump, but it would also be more than controllable enough to put pretty much the full magazine into one.

        Plus, once I finish my race gun inspired “holster” for it it will pack very similar to a 44 mag.

        The only real difference being my little monster runs with 5-6x more rounds on board.

      • Stuki Moi

        Tracers because they are so insanely natural and instinctive to lead and keep on a moving target during a full auto magdump when s$%^t scared. Keeping iron sights properly aligned on a charging bear in full auto, may be just another day at the office for Clint Smith. But that’s because he is Clint Smith. Not because it’s an intrinsically natural and simple thing to do. Besides, he could probably stop a bear charge with a sligshot.

        “Bear optimized,” or even regular fmj, 9mm will easily get to the most valuable real estate on a bear, the brain and frontal third cns structures. Hard cast .44+ heavies will give you second and third chances if you should miss the brain, by giving you a crack at shoulders, further back sections of the spine and, in the case of the biggest guns, perhaps even at breaking hip and thigh bones, busting the motor powering the attack. But 36 cracks at valuable frontally positioned vitals, sounds like a pretty good tradeoff to me.

        1 or 2 .44s definitely “can” put a bear down instantaneously, which is what you need to come away unscathed. But you’re dealing with a fairly small target for that to happen. Pretty much the brain. All I’m saying is that based on limited experience with both subguns and big revolvers, I’d estimate my chances were higher with the subgun. I am assuming the MACs, which I have exactly zero experience with, aren’t that much harder to shoot, and that much less reliable, than MP5s here.

        And heck, if nothing else, any justification for allowing increased civilian ownership of guns with a fun switch, can’t be all bad, right? 🙂

        • Joshua

          It’s an interesting concept, I have never heard of someone doing it, I have heard lots of stories of guys going out with their Glocks and in the after action autopsy the vet pulls a multitude of 9mm and/or .40 cal bullets from the bears muscle, none having penetrated into anything vital enough to kill the bear let alone stop it, but a full auto machine pistol discharging 30 some rounds where they got off, maybe half a dozen, is a slightly different ballpark. I would be interested to see the results if anyone could test it, but I probably would not volunteer to test it myself, I still question the tracers, most machine pistols have a frankly ridiculous rate of fire with magazines being emptied in less than two seconds, that’s not a lot of time to walk shots, but if your not losing anything to have them, why not?

        • roguetechie

          You know, I’d be willing to bet a +p+ 9mm makarov / .380 acp SJ-ESC round aka the Russian AP pistol rounds ought to do pretty damn good against bears at close range.

          SJ-ESC: Semi Jacketed – Exposed Steel Core

          SJ-ESC rounds are like a standard hollow point with a pointed steel penetrator wrapped in some sort of polymer sheath seated inside the hollow portion of the hollow point. When they hit something unarmored the hollow point mushrooms out into a nasty death flower while the steel penetrator keeps on cruising.

          Omfg I think I just found a “sporting purpose” for SJ-ESC rounds!

          Not that it would matter even a little because ATF would rather a school bus full of underprivileged children be eaten live on camera on Regis and Kathy Lee every morning forever than see even one “armor piercing” pistol round be made and sold to civilians!



    All this talk about Bears, reminds me of Americas, General Mattis, He has a Bear Rug in his Living Room, it isn’t dead, it’s just afraid to move. LOL

  • Colonel K

    The P35 is such an elegant design and fits the hand so well. It represented the pinnacle of handgun development during an age that still appreciated craftsmanship as the standard rather than the exception. Now we have Glocks, functional and utilitarian, but about as glamorous as a 2×4.

  • jcitizen

    I like the “kill three birds with one stone” idea of making that huge trigger guard – you get the front grip, guard, and you can get snow gloves into it easy. I loved the SM-!!-9 anytime I got to shoot it, but if they ever relax that damn ’86 law – I’d rather have a mini-uzi.