Soviet machine gun in a Finnish pillbox, or "A friend among strangers, a stranger among friends"

В previous article we took a brief look at the machine gun armament of the pillboxes historical retrospective. And now some follow-up material for readers already immersed in the topic.
Archive photo
In the Finnish archive of photo documents, well-known to historians, fans of military history, historical reconstruction and search engines, there are many photographs of the Soviet heavy machine gun DS-39. The same, model 1939, for the 7,62x54R cartridge, with air cooling, which is known as the brainchild of the weapons designer Degtyarev, designed to replace the morally obsolete machine gun of the Maxim system with water cooling.

DS-39
The machine gun did not gain fame among the troops, despite the fact that it was lighter, less bulky compared to water-cooled machine guns and had the ability to change the barrel. First of all, due to design flaws that led to the rupture of the cartridges when removing them from the barrel, as well as the inertial dismantling of the cartridge with a heavy bullet (including because Degtyarev was forced, at the request of the military, not to abandon the fabric cartridge belt used for firing from the Maxim machine gun) against the background of the ban "on the use of cartridges with a brass case (with a light and heavy bullet)" (quote from the Service Manual of the heavy machine gun model 1939). We will not describe the machine gun in more detail, fortunately, there is an excellent article.
Frankly speaking, there are very few Soviet photographs with DS-39 machine guns, and they relate primarily to the initial period of the war, but history has preserved for us such an interesting (from the point of view of the use of metal tape) photo of the crew of soldiers R. Tyulpanov and N. Sergeev on the Kalinin Front in 1942.

And then its production was curtailed in favor of the familiar "Maxim", and the machine guns produced were either lost forever or became enemy trophies. In total, more than 10 thousand machine guns of this type were produced, about 200 of which fell into the hands of the Finns both during the battles of the Winter War and at the beginning of the Great Patriotic War.
Of course, the Finns quickly figured out the advantages and disadvantages of the DS-39, moreover, Aimo Lahti had a hand in this as the “gunsmith of all Finland”, having developed and implemented the technology of converting the DS-39 to use the Finnish metal machine gun belt.

The photo does not show Aimo Lahti, but an ordinary Finnish infantryman.
As thrifty owners of trophies, the Finns used the DS-39 in the infantry version on a tripod mount to arm their troops, both in the version modified by their own gunsmiths and in the original version, therefore, having seen many years ago in the Finnish archive of photo documents photographs of our DS-39 in some kind of ball mount, clearly not for installation in armored vehicles (considering our own Finnish and acquired as trophies of all types with known characteristics and weapons), we became interested in its purpose.




Over time, we even managed to find a drawing.

At that time, all options were considered, including installation on an armored train, but it turned out that the Finns preferred to arm them with water-cooled machine guns and 40-mm Bofors anti-aircraft guns.

The option of installing it on warships was also eliminated.
So where was this method of mounting a machine gun used? Remembering the methods of mounting air-cooled machine guns in European and our pillboxes, which we mentioned in the article "Machine-gun armament of the pillbox", we assumed that this was some kind of Finnish fortification structure, fortunately the Finns wrote something like that on their own and international historical forums, but even here everything is not simple.
Firstly, 99% of the structures, even if they are relatively intact now, were disarmed during the war, and in the years after it were dismantled, or even simply cut up for scrap metal. This means that it is difficult to find out what everything looked like.
Secondly, in our and even Finnish museums there are exhibits with machine guns in pillboxes, these are reinforced concrete pillboxes with a rectangular embrasure, but these machine guns are water-cooled, our "Maxims" or Finnish M/32-33. The same applies to literary publications.
Here is a "Finn" from a pillbox on the Salpa Line in Finland, which has been converted into an open-air museum.

But the exhibition of our Karelian Front Museum in Belomorsk is similar, isn’t it (here the authors will be a little proud, since they have a slight connection to it)?

And this is what it looked like during the war.

It's funny, but even the Finns did not preserve a firing point in which an air-cooled machine gun would be installed using a design like the one in the archive photo, although there are written references to this.
The second widespread type of Finnish pillboxes are pillboxes with armored caps, here is a drawing of one of them, the most widespread.

To put it in perspective, about 1 armored caps were produced, and even taking into account that 2 armored caps could be installed in one pillbox (or even 3, as in the famous pillbox of the Mannerheim Line Sj-4 "Million"), and not all of them were installed, the figure looks impressive (to date, our team has inspected about a hundred of these pillboxes, although not all of them have retained their armored caps). By the way, there were several types of armored caps, 3 observation, 4 machine gun, and one of the types had its own subspecies, however, this is a separate topic. So, the machine guns in these pillboxes were, of course, mostly with water-cooled barrels, it is not difficult to imagine their required number.

Soldiers examine a Finnish armored cap with a machine gun after storming Medvezhyegorsk. Our team was able to identify it by the ruins of the sanatorium building in the background of the photo and the chosen shooting angle. On the Finnish diagram, it was designated V42

V42 today. The armored cap was sent to be melted down
By the way, in the armored cap, especially the single one (and there were also double ones), there is damn little space even for one.

The machine gunner has to stand either on a closed hatch, or like that cow in the bomb bay, risking falling into it.
The photo with two Finns in an armored cap and a photographer who somehow crawled up to them, is quite well-known, but it has, as they say, a reverse, less well-known side. The armored cap depicted in it is installed above a fairly spacious platform.


Find
Time passed, the study of the ball mount for the DS-39 was not a priority for us, and the collection of material about it occurred only incidentally (for example, Vadim Antonov's article "Another Degtyarev" was published, in which he also mentioned the Finnish ball mount with the DS-39 as an option for arming a pillbox) with other, more relevant and substantive topics, until our team's friend Evgeny, an avid fan of Finnish long-term fortifications from St. Petersburg, in the summer of 2024 found a characteristic ball in the forest near the armored cap of one of the Finnish pillboxes on the left bank of the Svir River and sent us a photo of it. Considering the weight of the armor steel, he did not risk his health to carry it out of the forest on foot for several kilometers, so as a result of our trip, the ball was taken out of the forest and studied, and with it the search for information was intensified.


Comes in and comes out. Just like Eeyore. Only turned 180 degrees.
First of all, it is striking that the ball seems to be the same, but not the same. That is, if you look at the diameter and shape of the hole for the machine gun barrel in a modern photo and a Finnish archive photo, you can clearly see that it is clearly not for the DS-39 with its ribbing of the barrel. But the option with installing the DT-29 in it is quite suitable. Something similar was in tank towers, dismantled from tanks of obsolete types and installed in our Karelian fortified region. And indeed, at the exposition of the MPC "Sestroretsk Line" we see this version.

The difference is essentially only in the shapes of the sighting holes. But there are other similarities.
With the new data we tried to generalize the information, consulted with St. Petersburg specialists in fortification and the Karelian fortified region in particular, Oleg Bushko and Alexey Shvarev, collected and looked at all the photos we took in Finnish armored caps on the territory of the Leningrad region and Karelia, and put forward our version based on the fact that machine gun armored shutters PZ-39 and PZ-40 were installed in the pillboxes of the Karelian fortified region.

PZ-39

PZ-40
And both of these machine gun flaps are structurally very similar to what is shown in the Finnish archive photo of the DS-39.
Version
Initially, our PZ-39 and PZ-40 were developed (a more technologically advanced and simpler version than the PZ-39), apparently, the Finns saw the PZ-39 somewhere (for example, when they fought to break through the Karelian fortified area and even managed to capture several pillboxes) and developed their own shutter (it differs from ours primarily in the number and location of bolts), and they developed their shutter not only for the DT-29, but also for the DS-39. The Finns have a round clip mount for the machine gun shutter (in our terminology) with 8 bolts in the technological holes provided in the armored cap (photos of the holes in them in Karelia and the Leningrad region, including from the armored cap in which the ball was found, are identical).


And in the same holes, only in 4 of 8, a standard machine for the Finnish “Maxim” M/32-33 was installed (photo from the Leningrad region).

But the ball itself could have been either our trophy for the Finns or Finnish.
The above facts show that Soviet engineers did not eat their bread in vain, and the Finns were not the first to experiment with this method of installing air-cooled machine guns. Moreover, the PZ-39 and PZ-40 machine gun shutters were installed in Soviet pillboxes to defend entrances and fire at approaches from the rear, and the Finns mounted their installations directly in armored caps as the main armament. Naturally, such a installation could be mounted in the wall of a concrete or reinforced concrete pillbox, or even a bunker. As it is done, for example, at the exposition of the St. Petersburg museum "Pillbox of the defensive line "Izhora"" in a pillbox with a PZ-40 machine gun shutter.


Our version received its confirmation, albeit partial (the use of an air-cooled machine gun as the main armament of a Finnish pillbox with an armored cap), from the historian, writer and local historian Bair Klimentievich Irineev, who published a photo of an armored cap with a ball mount installed for an air-cooled machine gun.

Conclusions
The history of the use of the Degtyarev air-cooled DS-39 heavy machine gun in combat in the Red Army is relatively short, controversial, but, like any deadly weapon, weapon, it has its contribution to the Victory. The enemy, having received it at its disposal for one reason or another, found this weapon not only suitable for its own use in combat, but also carried out a partial modernization, and provided for a wider application, borrowing interesting engineering solutions, trying to provide the troops with the required number of machine guns. It seems to us that this kind of approach always makes sense - to learn from the enemy, borrowing from him the best and most promising, and if need forces you to use ambiguous solutions, then do it not by blind copying, but by modernization and refinement.
P.S. The authors express their deep gratitude to their colleagues from the Internet resources “Karelian Fortified Region”, “Environs of Petersburg”, MPC “Sestroretsk Line”, the museum “DOT of the Defensive Line “Izhora” and “Military Album” for information and photographs.
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