Sosso 1941 Italian Prototype Pistol (Video)

The Model 1941 Sosso is a huge Italian experimental semiauto pistol designed by Giulio Sosso. It uses a short recoil locking mechanism and is chambered for standard 9x19mm Parabellum ammunition, but its more unusual feature is its magazine. Instead of using a traditional spring and follower, the magazine body holds a 21-segment chain, like a machine gun belt. The chain is rotated one position each time the pistol’s slide cycles. This would prevent problems related to magazine spring fatigue or varying pressure between the first and last round, but it also introduces a whole new set of potential problems.

Only 5 of these pistols were made (by FNA Brescia), with the other 4 of them being presented to significant Italian political and military figures. It was not adopted or put into any sort of serial production for reasons that should become very clear once the internals of the gun are seen. One could probably buy a dozen Beretta 1934 pistols for the cost of one Sosso…


  1. My thought, subsiding and rising again is,….is this a joke? But, what this does for person with interest in firearms is awareness of the enormous amount of effort, which ended up with today’s simple and prevalent tilt barrel lock up – and that is very beneficial. So many ‘wasted’ hours, days and years in between though!

    Thanks belong to narrator for his effort to decipher this creation.

    • “this creation”
      Sosso also designed sub-machine gun with high-capacity magazine, see images here:
      its capacity is estimated to be 70…80 rounds, also with peculiar magazine – it was double-stack although with… tumbler or whatever this element name is (see 2nd image from top in link). This weapon remain project only.

  2. Doing something different…Let the people see what genius you have had…Especialy in playing “Russian Roulette”.

    • “genius”
      I think that such magazine might actually work properly with rimmed cartridges or cartridges of peculiar shape, but 9×19 is NOT such cartridge. And anyway as more classic magazine for rimmed cartridges were actually developed (see Grendel P30) this niche is not empty.

    • Those pictures are gorgeous. I consider repeating topics good thing. It brings something new/update or same under different angle. Good observation btw.

  3. Nice. Not the design, which is as needlessly over-complex as the Grant Hammond pistol, but a wonderful view into how someone tries to come up with a better mousetrap. The magazine is especially interesting.

      • Most objections to the double-stack magazine as on the FN M1935 had to do with the single-position feed, which supposedly was less reliable than the double-position feed of typical double-column rifle magazines such as the Mauser or SMLE.

        What gets overlooked is that the Savage pocket automatics, with their 10-round magazines in 7.65mm Browning/.32 ACP, had been using just such an arrangement since before WW1 with no problems.

        And the retarded-blowback Savage system seemed to work perfectly well with considerably less “power in the mechanism” than a 9 x 19mm would generally be expected to possess.



        • I also wonder why two-to-one magazines persevere in their existence. Transition in columns is rather complex under static conditions. Much more sensible two-up all the way into feed-way are scarce, but they do show up. One such case is GSh18 pistol.

          I did some fun studies and found that it does not increase OA width significantly.

          • Probably because they work reliably enough in semi-auto pistols. A more interesting question is why they persisted so long in SMGs as they did. Although one must say that most reliability problems with for example the Sten magazines seem to be related to poor manufacturing quality and lack of finishing¹ . The again, the two-to-one system is probably more sensitive to such manufacturing defects.

            ¹ I have heard claims from people who trained with the Sten SMG in the 1950s and 1960s in the Finnish Army that many of the problems with the feed lips could be fixed or alleviated with a hand file.

          • Yeah, feed lips; that’s what it is. Sten in Gabchik’s hands failed miserably (not to say it changed history that much).
            With two stack pressure and kinematics are divided between them and it’s straight up. My best guess.

          • “why they persisted so long in SMGs as they did.”
            For me quite mind-boggling example is that American use double-exit stick magazine for their M1 Thompson sub-machine gun, but designed from scratch M3 Grease Gun used single-exit. Why they don’t design this weapon to be compliant with older Thompson magazines? Does Thompson stick magazines malfunctioned wildly?

            “One such case is GSh18 pistol”
            Is that true also for Yarigin automatic pistol?

            “it does not increase OA width significantly”
            Is there any connection between magazine shape (full-length double-stack vs necked double-stack like FN HP) and element codenamed Browning stirrup (if such is in construction of particular automatic pistol)

          • “Sten SMG”
            It was magazine-wise compatible with older British SMG – Lanchester. It is also possible that STEN affected some post-war development of sub-machine gun as being cheap and available as surplus – so if somecountry bought a lot of it might want to stay magazine-compatible, however I don’t have examples here.

          • Two into one requires approx 50% stiffer mag spring, as its movement at the bottom is less compared to how far it is shifting the top rounds.

  4. Weapon-powered small arms magazines should (I don’t say they do) have advantages in terms of high capacity and easy loading. No follower spring means extra room for cartridges, and low-effort filling: just keep pushing in stripper clips w/ minimum thumb-blistering and bad language.

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