Military Review

Yugoslav SSU Underwater Gun

The 20th century is officially considered the century of the birth of professional divisions of combat swimmers (divers-scouts), although the use of swimmers for military purposes was carried out before our era. Combat swimmers from such units solve combat missions to protect coastal fortifications and their own ships from the actions of enemy saboteurs. At the same time reconnaissance divers can be used to solve problems under water in ports, water areas and on the coast of the enemy. To counter swimmers, saboteurs from other countries, they needed a special weaponthat could shoot underwater. One of the models of such weapons was the SSU underwater pistol, which was developed in the interests of the armed forces of Yugoslavia.

In the late 1980s, the Yugoslav Navy considered the development of universal weapons, which were planned to equip combat swimmers. This weapon was supposed to shoot both under water and over water, and be silent. There was also a requirement for the possibility of firing a weapon with gloves. By that time, the Heckler & Koch P11 underwater pistol, which was strictly classified, had already become widespread in the West. At the same time, in the countries of the Eastern Bloc, such pistols were practically absent at that time.

At the same time, Yugoslavia has always shown a certain independence from the defense industry of the Warsaw Pact countries in the weapons-technical respect. For this reason, when creating weapons that were intended to arm combat swimmers, in Yugoslavia went their own way. Because of the internal contradictions that began to accumulate in Yugoslavia, and also because it was necessary to create weapons in a short time and inexpensively, and also to do it secretly, the secret service of the Navy of Yugoslavia placed an order for weapons in the Austrian city of Linz . This KB had a great experience in creating weapons. In those years, such developments in cooperation with foreign specialists were common for Yugoslavia.

Yugoslav SSU Underwater Gun

The advanced tactical and technical requirements for a new weapon looked like this:
- the possibility of using under and above water;
- small dimensions;
- reduced shot sound;
- effective range under water - 10 meters;
- effective range over water - 20 meters;
- water resistant at depths up to 40 meters / pressure up to 5 bar;
- the possibility of using weapons in diving gloves;
- The weapon was supposed to ensure the penetration of the standard scuba diving cylinders.

The assigned task did not frighten the representatives of the EBW design bureau from Austria and the design bureau experts successfully coped with it. Moreover, virtually no new weapons have been developed. In fact, the Austrian designers have developed only a special ammunition that could be used with all types of signal pistol, having a caliber 26 mm. Thus, the Austrian development in the interests of the Navy of Yugoslavia SSU (Self Supressing Unit) looks very much like a signal pistol. The fact that before us is something else, said only the arrow sticking out of the sleeve. To disperse the swept bullet used up to speeds up to 310 m / s, we had to use a special design of the cartridge case, since the maximum pressure that occurred in the bore of the signal pistol was only 110 bar.

It should be noted that from a technical point of view, the underwater projectile could be accelerated to speeds of more than 310 m / s, but in this case it would not be noiseless. The sound of a shot includes the 2 component: a sonic boom that appears when a bullet passes through a sound barrier and a gas bump is the noise of gunpowder gases rushing out. If the gas blow can be compensated by using a silencer, the sound impact is not. It is for this reason that the ammunition used in the SSU submarine pistol should have a subsonic speed.

SSU special munitions were made on the principle of high / low pressure pipes. This principle was developed as early as the Second World War in Germany, it was used to achieve the highest possible flight speeds with uniform and as low as possible pressure. In this case, the ignition of the powder occurred in the so-called part of the high pressure, which was connected with the barrel of the weapon (low pressure area) by several or one small hole. In the SSU, at the moment of ignition of the powder, pressure was generated up to 1200 bar, however, in the low pressure zone, which was connected to the high pressure area using four nozzles, the pressure was already less than 100 bar.

Due to this effect, boom acceleration was carried out evenly and "slowly." At the same time, the high-pressure chamber had a length of 10 mm and a diameter of 9 mm. Its volume was equal to the volume of the .38 Special caliber case. The ammunition developed by Austrian specialists was planned to be equipped with standard nitroporoch, however, the ignition process itself was implemented in a very original way. In the event that the powder was ignited in an ordinary way - by the method of pricking the cap of the cap, there would be a real danger that under pressure when the membrane was pierced, unburned powder granules could somehow end up in the nozzle holes, thus blocking them. At the same time, a further increase in pressure would be an uncontrollable process, which in turn would be a reason for reducing the accuracy of fire. It is for this reason that the charge of gunpowder in the SSU submarine pistol ammunition ignited in front.

To achieve this, the flame of a standard magnesium capsule was fed directly to the nozzles using a special “incendiary barrel”, which at the same time served as a nest for a capsule sleeve. Here the flame changed its direction, forcing the battle charge to burn out from the front. Despite this, the resulting pressure could not come out in front through the four nozzles available, since a special strong membrane made of plastic 0,6 mm thick was installed in front of them. The use of this membrane led to the fact that the pressure in the high-pressure chamber was sufficient for pure combustion of gunpowder.

Since the ordinary magnesium capsule was not waterproof, it took a non-standard solution aimed at preventing water from entering the cartridge from the back. To solve this problem, Austrian designers from EBW created a transition drummer. This drummer was used only to transfer the kinetic energy from the underwater pistol trigger inside the cartridge. At the moment of firing, powder gases with a very high degree of compression after penetration of the membrane exited to the low-pressure zone through the nozzle. This zone had a diameter of 20 mm and a length of 110 mm. In standard high / low pressure pipes, the low pressure area serves as a barrel, but in the SSU submersible pistol, in which an arrow of 8,7 mm thickness is used, this area was significantly larger. This was largely due to the suppression of the noise that was produced during the shot.

The idea of ​​Austrian specialists was to prevent hot, expanding powder gases from escaping, intercepting and blocking them inside. For this, a piston was used. The piston was located directly in front of the nozzles, it served to seal the low pressure area. The piston was set in motion by using hot powder gases that were flowing from the nozzles. In front of the piston in the center was the receiver of the tail part of the shot arrow, which he accelerates during his movement. In this case, the front guide of the boom is a hole, which is drilled in the head part of the cartridge. A special O-ring was put on the boom, which prevented water from entering the low pressure zone. At that moment, when the piston reached the extreme forward position under the influence of gases, pushing the boom in front of it, it rested against the front edge of the low-pressure chamber from inside, thereby preventing the exit of powder gases through the barrel of an underwater pistol, making the gun shot as quiet as possible.

When developing an SSU underwater pistol ammunition, high water density was taken into account, which has a very significant impact on their design. All underwater shooting ammunition is made as thin and long as possible, that is, arrow-shaped. In the case of the Yugoslav SSU, these are arrows that have a length of 122 mm with a diameter of 8,7 mm. In this case, two types of arrows were created, which differed from each other only in the strength of the rod used. The arrows of the first type behind the hardened steel head had an aluminum rod with a wall thickness of just 0,5 mm. The arrows of the second type were distinguished by a greater wall thickness of the tail — 1,75 mm. The mass of ammunition was 12 and 21 grams, respectively. In flight, the stabilization of the created shells occurred along the arrow principle, as well as for the shells of shotguns, which were widely distributed from 1910 onwards.

After 5 prototypes were created, a decision was made to conduct their tests in order to make sure in practice that they meet all the requirements of the specification. Since the city of Linz was not far from Salkammergut with its deep lake, they decided to approach the solution of the problem very pragmatically in the EBW design bureau, they just rented a water bike and went to the lake. In the middle of the reservoir, with the help of a rope, the unloaded cartridge dropped to a depth of 20 and 30 meters. After that, it was removed from under water and spent external drying. Then the body of the cartridge was disassembled and the tightness of the structure was checked. Approximately 8 hours of work under the scorching sun took to make it finally clear that the principle of sealing will be maintained at a depth of 70 meters, as well as at a pressure that is higher than the required by 60%.

Then, of course, it took a series of firing tests. Shooting was carried out from a massive launcher. Shooting proved the fact that the dimensions of the body of the cartridge were calculated correctly. The hull was so strong that you can shoot a cartridge from SSU even without a barrel, despite the pressure in the 1200 bar in the high-pressure zone. With this, only the trigger release made itself felt, this sound was louder than the shot itself. During the tests, shooting was conducted on standard scuba tanks made of steel. In all cases, without exception, these cylinders were pierced.

A check on the convenience of servicing an underwater gun in thick diving gloves showed that the weapon was easy enough to use, the test was simple. At the same time, accuracy tests had much higher requirements. It was relatively easy to verify the accuracy of SSU, which was fixed in a special machine. But for the developers of EBW, real shooting sensations were important. In this case, the characteristics of a shot from this underwater gun can be described as very unusual. Although at the first moment the SSU has an average power (for a signal pistol) recoil force, at the moment when the piston beats into the front wall of the liner, there is a counter-moment, which is much more noticeable. At the same time for the weapon at the time of the shot it does not matter.

When it turned out at the very beginning of 1991 of the year that the situation in Yugoslavia was leading to civil war, the development of the SSU submarine gun was almost immediately stopped by both the Yugoslav Navy secret service and the EBW development company. At this point, it was possible to collect all the 5 suitable for conducting shooting samples of the gun. Three of these prototypes were turned into special split weapon models.

In terms of technology, SSU development has been completed. The cartridge could be put into mass production. The changes could only relate to the use of different materials, since in the process of production all the steel parts, with the exception of the high-pressure chamber, which was made of special high-grade steel, could be replaced with plastic and aluminum, which had the best resistance to saltwater.

As a result, this weapon turned out to be unclaimed neither by the Navy of Yugoslavia (the country was falling apart), nor by the Warsaw Pact countries. At the same time, in the USSR, by that time, new, more promising models of weapons were created for underwater shooters, including store-type samples. At the same time, the practice of recent decades shows that maritime units for special purposes, and with them, underwater military operations in so-called asymmetrical military conflicts play practically no role. In this aspect, the created SSU is an original development, a good weapon-technical idea, which, having proved its technical soundness, did not go into the series.

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  1. Bongo
    Bongo 1 December 2014 07: 48
    In order to achieve this, the flame of standard magnesium capsule led directly to the nozzles ...

    What is this "standard magnesium capsule" what Can someone tell me?
    1. Mister X
      Mister X 1 December 2014 12: 39
      Quote: Bongo
      What is this "standard magnesium capsule"

      May be meant magnesium POWDER type MPF-3, MPF-4, which is used in signal cartridges.
      1. Bongo
        Bongo 2 December 2014 05: 48
        Quote: Mister X
        May be meant magnesium POWDER type MPF-3, MPF-4, which is used in signal cartridges.

        In the text Michael, we are talking about "standard magnesium capsules", it is clear that such in nature do not exist. Magnesium powder mixed with oxidants is absolutely insensitive to mechanical stress.
        1. Mister X
          Mister X 2 December 2014 13: 21
          Quote: Bongo
          In the text Mikhail, we are talking about "standard magnesium capsules", it is clear that such in nature do not exist. Magnesium powder mixed with oxidants is absolutely insensitive to mechanical stress.

          Found another version of the text.
          It says so:

          If the powder were ignited in the most usual way by a primer located at the back, there would be a danger that after the destruction of the membrane of the primer, the still non-ignited powder grains could get into the holes of the nozzle block and plug them.

          In this case, a further increase in pressure would become uncontrollable, and the consequence could be poor accuracy.
          Therefore, the powder charge of the cartridge SSU ignited in front.

          To achieve this, flame standard reinforced primer With the help of an igniter tube, which also serves as a pilot filter, it is transmitted directly under the nozzle block.
          1. Bongo
            Bongo 3 December 2014 14: 02
            Quote: Mister X
            To achieve this, the flame of a standard reinforced capsule using an igniter tube, which simultaneously serves as an ignition filter, is transmitted directly under the nozzle block.

            Thank you Michael! good In general, I assumed yes Unfortunately, the "author" thoughtlessly "ripped off" the article without even thinking about the logical inconsistencies.
            1. Mister X
              Mister X 7 December 2014 18: 00
              Quote: Bongo
              Unfortunately, the "author" thoughtlessly "ripped off" the article without even thinking about the logical inconsistencies.

              Most likely, he rewrote the original text in his own words, but technically the author is slightly limping.
              1. Bongo
                Bongo 8 December 2014 05: 35
                I read this back in 2009.
    2. vodolaz
      vodolaz 2 December 2014 02: 26
      Funny design, but in the photo is still our IDA-71 and SPP-1 gun. I didn’t hold a gun in my hands, but I talked with the IDA in the army)
    3. Mooh
      Mooh 2 December 2014 23: 54
      What is this standard magnesium capsule? what Can someone tell me?

      A crooked article is this. Apparently some aunt was translating from the Aglitsky.
      special o-ring

      In Russian - it will be an omentum.
  2. Rzhevsky
    Rzhevsky 1 December 2014 08: 27
    It's funny to shoot from a low-noise pistol at the cylinders! Very "low noise" effect.
    Another question to the Yugoslavs, you still have to get into the cylinder. By the way, the attackers will have aluminum cylinders!
    Thank you for the article, an unknown instance, looks like a Belgian cartridge.
    1. hoard
      hoard 1 December 2014 09: 20
      Quote: Rzhevsky
      By the way, the attackers will have aluminum cylinders!

      I don’t think so. Now rebreathers are in fashion, not cylinders)))
      1. Rzhevsky
        Rzhevsky 1 December 2014 09: 26
        And what canceled the cylinders in the rebreather? In NATO rebreathers exclusively aluminum cylinders of 1-2,5 liters. Learn the materiel.
        1. hoard
          hoard 1 December 2014 10: 37
          Teach yourself! - And I have long since unlearned and even practiced))). Shoot under water on a 2l cylinder, often covered by a casing? This is unrealistic. The terms of reference clearly meant ordinary scuba gear. In general, a very strange story with the terms of reference and development. Since the mid-70s, already in the USSR, SPP and APS were used (they are in the first photo). Has the USSR really not shared with Yugoslavia? However, it may be - Yugoslavia blew neutrality and was not included in the Warsaw Pact.
          1. Mister22408
            Mister22408 5 December 2014 21: 42
            "To shoot underwater at a 2L cylinder, but often closed by a casing? It's unrealistic." ... It will be a disaster if you didn't hit the cylinder, but only the diver. Probably - "failed". Usually people beat on a can from "VPV" exercise under water. After practice, you know the dimensions.
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    3. Master_Lviv
      Master_Lviv 2 December 2014 09: 48
      It is understood that from a low-noise UNDERWATER pistol, cylinders will be fired under WATER, so your fun is not entirely clear ...
  3. gross kaput
    gross kaput 1 December 2014 11: 31
    Quote: magot
    Has the USSR really not shared with Yugoslavia?

    Yugoslavia, starting with Tito, jumped from bed to bed as a prostitute, therefore, she didn’t really get new equipment from the USSR, and there’s no need to talk about secret models, even the most faithful allies like the GDR didn’t receive special weapons, and at least APS and SPP and appeared in the 70s, but were declassified, if insanity doesn’t fail me, in 1989, that year was generally fruitful for declassifying special shooting - SMEs, PB, APB, silence, canary - that’s for sure, like BCC with AS and underwater shooting.
  4. padonok.71
    padonok.71 1 December 2014 13: 11
    Quote: gross kaput
    while APS and SPP, although they appeared in the 70s, were declassified, if insanity doesn’t fail me, in 1989 that year was generally fruitful for declassification of special shooting - SMEs, PB, APB, silence, canary - that's for sure, like and BCC with speakers and underwater shooting.
    By that time, all these things were already a half-secret secret.
    1. gross kaput
      gross kaput 1 December 2014 21: 37
      I don’t think you need to explain about our secrecy.
  5. bazilio
    bazilio 1 December 2014 14: 42
    I think for Yugoslavia pretty well. A long projectile is the right decision ... but of course, it’s still a long way to NGN, but I’m generally silent about APS
  6. xren
    xren 1 December 2014 15: 51
    Quote: Rzhevsky
    It's funny to shoot from a low-noise pistol at the cylinders! Very "low noise" effect. Another question for the Yugoslavs, they still have to get into the balloon. By the way, the attackers will have aluminum cylinders!

    Well, the required armor-piercing is simply set. And getting on the ball is just a miss. But even with such performance characteristics it is dangerous.
  7. Zigmars
    Zigmars 2 December 2014 10: 16
    By that time, the Heckler & Koch submarine P11 pistol, which was strictly classified, had already been widely used in the West. At the same time, in the countries of the Eastern bloc such pistols at that time were practically absent.

    But what about the SPP-1960 pistol, designed back in the late 1s, and the submarine automatic submachine gun APS from TsNIItochmash developed in the mid-1970s ?!
    1. Rzhevsky
      Rzhevsky 3 December 2014 00: 41
      The fact is that our developments remained with us. And their P11 quickly fell into the hands of the right people. Now there is information on P11 in the network!
      With our developments, everything is better, the less they know, the better.
      I will tell you, Partners quietly smoke on the sidelines.
      According to rebreathers, the Davis apparatus, they were the first in development and application. And how many countries except Russia use regeneration in the device?
      Devices without cylinders are possible! But this is a separate issue, and a very big one.
      All in good time.
  8. Svetovod
    Svetovod 2 December 2014 16: 36
    Once I watched the TV series "24 Hours", I saw this thing. An evil terrorist (a Serb in the script) used him as a crossbow to remove the guard. On land and near. I thought that ethno is a purely American Jamesbond thing, annette - Serbia has made it.
  9. Rzhevsky
    Rzhevsky 3 December 2014 00: 53
    Yugoslavs and Yugoslavs in Africa!
    Our tutaks made a pistol for SMEs, made at the institute. On his new underwater pistol, they replaced the 7,62x39 bullet with an arrow for firing under water.
    Since there is no information on the network, it means that the gun is workable!
    China, by the way, is copying the most successful things. Aps copied!
    1. Mister22408
      Mister22408 5 December 2014 21: 49
      Bullet 7.62x39? Maybe a cartridge? SMEs - how many trunks? And in SPP-1 there are four, and the caliber is completely different, you can’t even remember about USM - everything else.
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