There were a lot of attempts to create a submachine gun that could be worn really hidden by people of even the most modest dimensions, without arousing suspicion from others, and just a variant of a compact submachine gun, there were a lot. Among such samples there were a lot of interesting models, but more often than not they did not receive even minimal distribution, remaining unclaimed. The fastest way to find common reasons for the fact that really compact submachine guns did not get widespread is not to find, since each such model of weapon had its own negative qualities that did not allow it to become widespread. Sometimes this was low reliability, sometimes the cost of production, and sometimes just the inability to fire normally from a weapon due to the peculiarities of its design. There were also such samples in which all these "diseases" were present together. This was primarily due to the fact that the designers were very creative in their work and, in pursuit of reducing the size, even came up with their own versions of the automation system, but taking into account the fact that the new designs were not worked out and were not tested, there is nothing strange that problems appeared. In general, I personally think that the creation of new samples with a fundamentally different design is a very useful thing, one might even say that it is more useful to create one bad, but unique sample than 100 according to already known and proven schemes, which will not add information to the knowledge box of designers absolutely nothing. An unsuccessful sample, even if it is generally "stillborn", will show everyone that this should not be done, or it is necessary to wait until the development of science reaches the level when everything conceived can be done with a sufficiently high quality and relatively cheap. In this article, I propose to get acquainted with a similar sample, which is quite simple, has an original automation scheme, is compact, but at the same time could not become widespread. We are talking about the MGD submachine gun and its version chambered for 9x19 MGD PM-9.
The author of this weapon is the Frenchman Louis Debuy, who was tasked with creating a light and compact submachine gun for the M1935 pistol cartridge with the metric designation 7, 65x20, which was then common in France. It was at the end of the 40s, which adds even more to the weapon, or rather to its author, respect, since usually the original designs of weapons date back to the end of the nineteenth - the beginning of the twentieth century, later everyone preferred to adhere to the already worked out designs of weapons. It even got to the point that the weapon was put into series, but very small. Subsequently, the cartridge 7, 65x20 was replaced by the 9x19, which required a change in the weapon itself, but since the characteristics of the ammunition are different, the automation of the pistol itself had to be recalculated. Unfortunately, it was difficult to adapt the weapon for a more powerful ammunition. To achieve at least some reliability and durability from the weapon, a very high accuracy of fitting and processing of parts was required, which was not at all cheap. As a result, only about 10 weapons were fired chambered for 9x19, after which everything was over.
Since the ammunition 7, 65x20, one might say, was the main one for this submachine gun, then, I think, a couple of lines should be written about it, especially since this cartridge was once a fairly common ammunition. This ammunition was developed in 1925 for one of the new pistols, but neither the weapon nor the ammunition was adopted at that time and did not receive distribution. Subsequently, the cartridges were slightly changed and were put into service under the designation M1935, in this type of ammunition was used in the submachine gun. This cartridge was equipped with a bullet weighing 5.6 grams, which, when fired from an MGD PP, moved at a speed of 305 meters per second, that is, the kinetic energy of the bullet is somewhere around 260 Joules, which was naturally not enough to meet the needs of the military. Nevertheless, until the end of World War II, these ammunition held out, and in 1945 they were replaced by 9x19, although not immediately, which can be seen at least from the considered PP sample.
Since the designer conceived the virtually impossible, namely the creation of a compact version of a submachine gun with a full barrel length, he had to dream up a little. The solution was found both standard and somewhat unusual implementation. First of all, it was decided to introduce a folding frame stock into the design of the weapon, which was at the same time an emphasis for the shoulder and a handle for holding. The solution turned out to be far from the most convenient, but it made it possible to significantly reduce the dimensions of the weapon in the folded position. Despite this, the submachine gun had one more detail that significantly increased its dimensions and did not allow carrying weapons hidden and comfortable, this detail was a store. Of course, it was possible to take a simpler path and offer to carry a submachine gun without a magazine, but then additional time would be required to bring the weapon into combat readiness, and it was already great because of the folding butt, without which it was simply impossible to fire. For this reason, the designer decided to introduce a rotary magazine receiver into the design of the submachine gun, which made it possible to place the magazine parallel to the barrel of the weapon when turning. Naturally, in this case, it was impossible to fire from the weapon, except to shoot the cartridge remaining in the chamber.
But that's not all. In order to make the weapon more compact, the designer decided to use a not quite ordinary automation system with a semi-free breech. The lightweight bolt of the weapon moved along a completely normal trajectory, but its free movement was limited by one spring-loaded part, namely a disk with a figured protrusion for the bolt stop. The disc itself was connected to a torsion spring. Thus, when fired, the powder gases pushed the bullet forward, and through the sleeve forced the bolt to move back, and although it was light, its weight was enough to store the energy received from the powder gases for a complete recoil. In the process of moving the bolt back, the spent cartridge case was removed from the chamber and thrown away, and the bolt itself, resting against the figured cutout, forced the spring-loaded disk to rotate, compressing the return spring. Separately, it should be noted that the force for turning the shutter applied differently at each point of its stroke, which made it possible to significantly reduce the recoil of the weapon, however, it is impossible to talk about the absence of recoil, since the scheme of operation of the automation was still shock. In addition, the movement of the disc, despite its not so large mass, affected the convenience of holding the weapon, it was noted that the barrel of the submachine gun leads up quite strongly when firing in bursts, although this phenomenon seems to me to be very far-fetched.
The barrel length of the weapon is 213 millimeters. The total length of the weapon with the butt folded is 359 millimeters, with the unfolded stock 659 millimeters. The weight of the submachine gun is 2, 53 kilograms, and the rate of fire is 750 rounds per minute. The weapon is fed from detachable magazines with a capacity of 32 rounds. Taking into account that the weapon used not the most successful cartridge 7, 65x20, the effective range of use is not more than 100 meters, but taking into account the not very convenient butt, which is used, like the handle of the weapon, it is unlikely that this distance would have reached more than 150 meters even with condition of use 9x19. Still, whatever one may say, but ergonomics also plays a significant role in the effectiveness of weapons, especially when it is close to zero.
It is difficult to say whether the designer managed to achieve the set task. On the one hand, the sample for its years turned out to be really compact when folded, but was this compactness worth such sacrifices? Although, on the other hand, a compact submachine gun is a rather specific weapon and is not suitable for widespread distribution, but where such a weapon may be needed, something can be sacrificed for the sake of compactness.
