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Antitank weapons used by the Finns in Winter War

Antitank weapons
used by the Finns in the Winter War

Part I

 

In Part II

  • Antitank rifles
        20 mm L-39
        14 mm m/37 "Boys"

  • Special
        13 mm AT-machine gun L-35/36
        Molotov Cocktail
        Satchel charge
        Mines
        37 mm Infantry Guns

All of the AT-guns have in their official Finnish designation the abbreviation "Pst" included.
"Pst" is an abbreviation from the Finnish term "panssarintorjunta", which means antitank.

 That "Pst" abbreviation wasn't always used, unless there was another similar caliber gun in use (e.g. as a field artillery piece or as an AA-gun), and there was a real chance to mix the two different weapons with each other.
Thus I use in the text the designation without the "Pst" abbreviation.

e.g. 37 PstK/36 is the same gun as 37 K/36

I have included the different gun types in the order reflecting the numbers used,
e.g. the Bofors 37 mm was the most widely used

 

 

Antitank guns

 

The 37 PstK/36

The 37 mm Bofors AT-gun model 1936, photographed in the Military MuseumThis picture shows also the carriage and the "driver"
(The gun is attached to the horse drawn front wagon)

This Swedish gun design, made by Bofors, was at its time one of the most sophisticated AT-guns in the world. The first prototype was produced in 1932, and the final version in 1934. The weapon was accepted into the Swedish Army as the "37 mm Pansarvärnskanon m/34". In time, some improvements were made to the original type, resulting in the m/38 and m/38F.

In 30 October 1936, the gun was accepted as the primary AT-weapon for the Finnish Defense Forces, and the license was bought. In Finland, two factories were to start the production of the 37 K/36. One was Tampella, and the other VTT ("Valtion tykkitehdas", "The State gun factory" in English). Oy Crichton-Vulcan produced the gun mount and the wheels for the guns. In addition to Finland and Sweden, many other countries adopted the Bofors gun, among them Denmark and Poland.

The first order from the Finnish Army, 156 guns, was placed in 1938, with the two factories. As there were constant problems in getting the production started, Finland bought also guns from Sweden, many of which were of the newer m/38 type.

The wavelike upper edge of the Swedish built m/38 gun
Picture source:
"Marskin panssarintuhoojat", p.213

A picture showing the uneven edges of the shield of the m/38 gunThe main difference between the Swedish m/38 and Finnish m/36 (and also the Swedish m/34) was that the former had an improvement that wasn't adapted to the Finnish production: a wavelike upper edge of the gun shield, making it easier to camouflage and harder to spot (see the picture on the right). Finnish produced guns didn't have this feature. The gun shield was 4 - 5 mm thick (weight 46 kg), but unlike the current German and Soviet designs, the Bofors gun shields didn't offer any protection from the side.

The guns that were bought or supplied from Sweden had the targeting scopes attached. For the Finnish produced guns, the optics had to be bought from abroad, so for financial reasons, they fought the Winter War relying on their collimators. This wasn't as bad as it's sounds, as experience showed that up to medium range of some 400 m, the scope wasn't very superior. In fact, in the dark hours, the collimator was better as the lens of the scope easily frosted over in damp air.

One 37 K/36 photographed after the war, note spots of white paint on the wheels
(Picture source: "Talvisodan Historia 1", p.169)

At the start of the war, the Finnish forces had the following number of 37 mm Bofors guns

Guns bought from Sweden 37 K/34 48 guns
Produced by Tampella 37 K/36 18 guns
Produced by VTT 37 K/36 32 guns
Total 98 guns

Note that most Finnish arms tables give the figure 112 guns, as the number of 37 mm AT-guns in Finland on 30 November 1939. The extra 14 guns were old Rosenberg (37 Jv.K/15) and Obuhov (37 Jv.K/14) 37 mm infantry guns. They were counted in the same category as the Bofors guns, even as though AP-capability of those guns were nearly nonexistent (at a range of 200 m, the solid AP projectile penetrated some 10 mm of armor at an 90° angle).

By 13 March 1940, the Finnish troops had received 222 (including the 98 guns at the start of the war) 37 mm AT-guns. The figure includes the 17 guns (37 mm K/34) of the SFK ("Svensk Frivilligkåren", the Swedish Volunteer Force).

(In Finland, when the production of 37 mm AT-guns was canceled during the Continuation War, a total of 355 guns had been produced, 300 by Tampella and 55 by VTT).

 

A camouflaged 37 mm /model 36 Bofors in action, in Lapland
(Picture source:"Marskin panssarintuhoojat", p.213)

As the Finnish infantry lacked AT-rifles, the AT-guns had to be deployed relatively close to the front-line, resulting in heavy losses. Of the 37 mm AT-guns, 66 were lost in the Winter War for various reasons, a little over a third of the total number of 37 mm AT-guns.

As the domestic shell production was also in trouble, the base stock of shells, 32 000, was bought from Sweden. Note that throughout the Winter War, Sweden was the main source for shell supply. Even during the Continuation War some shells had to be bought from abroad.

The gun proved highly effective. The AP-projectile penetrated the armor of all Soviet tanks used in the Winter War (with the exception of the Soviet heavy tank prototypes, which were tested, but in general, the statement is true).

While the gun was mostly used at ranges of 400 - 600 meters, the unofficial record was 1 700 meters(other source says 2 000 m), when a gun of the 7th AT-detachment (Pst.Os.7 in Finnish) destroyed a T-37 on the ice of Lake Ladoga near Taipale.

 

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CHARACTERISTICS OF 37 PstK/36

Caliber:
Barrel length:
Weight in firing position:
Height of barrel in firing position:
Gun height:
Width:
Traverse:
Elevation:
Max. ROF:
Practical ROF:
Muzzle velocity:
Max. range:
Max. practical range vs. tank:
Max. practical range vs. inf.position:

37 mm
45 Cal. or 1 736 mm (incl. muzzle brake)
370 kg
625 mm
1 030 mm
1 090 mm
26°
- 10° , + 25°
30 r.p.m.
12 r.p.m.
830 m/s
4.5 km
0.9 km
1.5 km
 

The gun had 4 different types of rounds.
- AP-shot ("panssariammus" in Finnish), weighed 1.45 kg , from which the projectile weight was 0.7 kg
- AP-HE shell ("panssarikranaatti" in Finnish)
- Fragmentation shell ("sirpalekranaatti" in Finnish)
- practice shot ("harjoitusammus" in Finnish)
(During the Continuation War, a batch of "phosphorous incendiary shot" was also produced, "fosforisytytysammus" in Finnish).

 

Penetration
AP-projectile (0.7 kg) with the muzzle velocity was 870 m/s
when the armor plate was at an
60° angle

  300 m 500 m 1 000 m
Gun manual 40 mm 33 mm 18 mm
Test firing in 1943 42 mm 37 mm 28 mm

(Table source:"Marskin panssarintuhoojat", p.113)

Note: in the test firings, the shot used was an upgraded AP-shot with a muzzle velocity of 880 m/s

Note that as no data is available from the armor plate hardness, the performance isn't automatically comparable to the penetration values of other weapons, especially if the used source is different.

 

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The firing table of the 37 mm Bofors
with the model '34  AP-shell

Range elevation
(in mils / points)
flight
duration (sec)
zenith during
flight (m)
effect of 1 m/sec side wind
mils/points centimeters
100 6 0.13 0.02 0.1 2
200 7 0.27 0.12 0.1 4
300 8 0.42 0.25 0.1 6
400 9 0.58 0.47 0.2 8
500 10 0.76 0.73 0.2 12
600 11 0.95 1.1 0.2 16
700 13 1.15 1.7 0.3 20
800 14 1.36 2.3 0.3 26
900 16 1.59 3.2 0.4 32
1000 18 1.83 4.3 0.4 40
1200 22 2.35 7.1 0.5 60
2000 47 4.83 31.0 0.9 180

 

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The 45 mm guns
(45 PstK/32, 45 PstK/37 and 45 PstK/38)

 

The basic m/32 gun The improved model 37 with the new suspension

In the early 1930s, the Red Army realized its need of an AT-weapon. At the time, the Soviet Union had working trade relations and quite close military cooperation with Germany.

The Red Army acquired German 37 mm AT-guns, produced by Rheinmetal. The Soviet planners were quick to develop their up-gunned version of the gun, resulting in the "45 mm Protivotankovaja Puska obr. 1932 g". The sights, the caliber and some manufacturing solutions were changed, but otherwise the gun was a close copy of the original German gun.

 

While the first production models had all wooden wheels, rubber tires were introduced with the rim of the wheel having spokes. The m/32 had many unsatisfactory characteristics, and some of these were sorted out in the newer m/37 model. The most notable changes were:

A Finnish crew training with a captured 45 mm AT-gun, in January 1940
(Picture source: "Talvisodan Historia 4", p.184)

- The axle of the m/32 had no suspension, reducing transport speeds (traveling gear). In the m/37, a new suspension was added, adding suspension cylinders between the axle and the wheels, increasing the width of the gun by 24 cm. A triggering mechanism was inserted into the hand wheel of the elevation mechanism. Some other modifications were made to the traverse mechanism. The loading mechanism was improved by a new breech block (making it semiautomatic) thus increasing the rate of fire. Also, the construction of the wheels was changed.

The next modification to the m/37 was another change to the suspension. This was made in the following year, and while the modification left the gun and the characteristics mostly unchanged, it still was enough change to the logistics (maintenance & spare parts), that the new model was designated as m/38. 

 

The first Soviet 45 mm AT-gun was captured by the Finns in the early days of the war. The gun was immediately noted to be a good weapon. The construction was somewhat simpler than in the Finnish guns, but it was still regarded as well suited for Finnish use. The larger caliber resulted in greater penetration values than for the 37 mm guns, making the 45 mm AT-gun the best AT-weapon of the Winter War.

During the Winter War, 125 guns were captured (either in good order or that could be repaired). I don't have exact figures of how many were used in combat, but after many were lost in the last battles of the war, and many were stripped for spare parts, the exact number on June 1940, were 93 guns (most were m/32 guns).

All captured guns, that were in good shape were immediately sent either to the front line troops, or to the AT-gun Training Center ("Panssarintorjuntatykkikoulutuskeskus" or "Pst.Tyk.Koul.K") in Hämeenlinna.

Thousands of shells were also captured, and in May 1940, there still were nearly 59 000 rounds in Finnish stores, and soon after the first order to VTT ("Valtion Tykkitehdas", "The State Gun Factory" in English) was given, for the domestic production of 45 mm shells.

(At it's peak, during the "trench war phase" of the Continuation War, the Finnish Army had 671 guns in use or in store.)

 

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CHARACTERISTICS OF 45 PstK/32

Caliber:
Overall length:
Barrel length:
Weight in firing position:
Height:
Width:
Traverse:
Muzzle velocity:

45 mm
4 260 mm
46 Cal. or 1 970 mm
425 kg
1 250 mm
1 370 mm
1000 mils
330-760 m/s
 

AP-shell 2,4 kg, from which the AP-projectile weight was 1.43 kg
HE-fragmentation shell 2.8 - 2.9 kg
Canister shot 2.2 kg

 

Penetration
AP-projectile (1.43 kg), with the muzzle velocity of 760 m/s,
when the armor was at an
60° angle

100 m 500 m 1 000 m 1 500 m 2 000 m
43 mm 35 mm 28 mm 23 mm 19 mm

(Table source: "Guns vs. Armor"-website, by D.M.Honner)

Note that as no data is available from the armor plate hardness, the performance isn't automatically comparable to the penetration values of other weapons, especially if the used source is different.

 

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The 25 PstK/37
"Canon leger de 25 antichar SA-L mle 1937"

The French 25 mm Model 1937 AT-gun
(Picture source: "Talvisodan Historia 4", p.260)

In the early 1930s, when the majority of tanks were still light tanks, a new 25 mm AT-gun was designed for the French Army. This new gun, which was designated as "Canon leger de 25 antichar SA-L mle 1934" became later on the standard AT-gun of the French Army. It was produced by Hotchkiss.

The older m/34 gun, which had nearly identical performance, but was considerably heavierA few years later, a lighter and technically more advanced version was made, the modele 1937. The characteristics of this newer model were similar to those of the mle 1934. The mle 1937 was mainly produced by the Puteaux arsenal.

However, the small caliber, relatively short range and the small projectile weight (and of course small penetration value) made these guns nearly obsolete even at the start of the war.

 

If glanced at quickly, both guns look very similar, as both types had two carriage legs and a funnel-shaped flash suppressor. Distinctive features between the two types were:
- the shield of the m/34 is a bit weird looking two piece shield, while the m/37 had a single armor shield with vertical hinges (the shield could be folded during transport)
- the m/34 had metal disc wheels, while m/37 had cartwheel type steel wheels
- the m/37 has a long recoil spring visible around the barrel, near the shield
- the m/37 had a funny looking flange plate ("laippalevy" in Finnish) in the flash suppressor

Finland managed to buy 50 guns (with 25 000 shots) from France, and the first batch of 40 guns left France on 22 January 1940. The guns arrived via Trondheim in February. As the fate of the country was being settled, roughly half of the 40 guns were hurried to the fronts. The 10 remaining guns never reached Finland in time, the final delay being caused by Germany's invasion of Norway.

In June 1940, the total number of these guns was 37. Three guns were lost in the last few weeks of the war.
(Later on, in Fall 1940, Germany offered 200 guns at a reasonable price from their war booty stores. Finland accepted and thus after the shipment arrived in December 1940, the number of 25 mm AT-guns was at its peak 237 guns, from of  which 133 were m/34 and 104 were m/37).

The gun was said to be accurate and the sights were good. The muzzle flash was very small, making the gun hard to detect. However, the penetration was lousy when compared to the weight of the gun. The gun was easy to use, and the loading mechanism was simple, but the other mechanisms were more complex and not very reliable.

 

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CHARACTERISTICS OF 25 PstK/37

Caliber:
Barrel length:
Weight in firing position:
Traverse:
Elevation:
Muzzle velocity:
Max. (theoretical) range:

25 mm
77 Cal. or 1 810 mm
310 kg
37
°
- 10
° , + 26°
900 m/s
Max. range: 1800m
 

The Finns had 2 different AP-projectiles for this gun.
1) the AP-shot (solid shot)
2) the AP-shot with tracer.
The ballistic and AP-performance of both types were virtually identical.

 

Penetration
For the model '34 gun (which had nearly the same performance as the model '37 gun)
the penetration with the AP-shot (0.32 kg), when the armor plate is at 60° angle

100 m 500 m 1 000 m
35 mm 29 mm 20 mm

(Table source: "Guns vs. Armour"-website, by D.M.Honner)

Note that as no data is available from the armor plate hardness, the performance isn't automatically comparable to the penetration values of other weapons, especially if the used source is different.

E.g. in the fighting north of Ylä-Sommee (some 10 km south of Viipuri), in late February, a gun team with a 25 mm m/37 AT-gun was attached to the II/JR 15. The team fought a duel with a BT-7 (it's possible that the tank had problems pinpointing the gun, as the muzzle flash was hard to detect). Even after scoring 12 apparently ineffective hits, the tank was still firing all weapons. Only after the 13th shot found the mark, the tank suddenly stopped moving and the guns went silent as black smoke began to come out from the engine compartment of the knocked out a BT-7. While I don't have information about the range of the engagement, the AP-performance of the 25 mm AT-gun sounds questionable as the BT-7 had a maximum armor of 22 mm at an 72° angle (the armor of the model 1937, which had the best armor. That particular tank could have also been a less armored version).

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The 20 PstK/40
(The 20 mm "Madsen" automatic cannon)

The 20 mm Madsen gun on a low silhouette AT-carriage
(The gun in the picture is on the wheeled AT-carriage, note that Finland received those carriages only after the war)

The Danish 20 mm automatic cannon, produced by the Madsen factory, was one of the most successful light cannons of the 1930s.

After the war started, the Finnish Navy and the Air Force immediately expressed their interest of acquiring Madsen cannons. In early December the Navy asked that if it could borrow 4 guns, but the request was denied. The Danish government was very careful in it's open stand on this conflict, fearing a possible reaction by Germany (very understandable, regarding Denmark's location). After this, the situation remained quite unclear for a long time.

In mid-January the Finns heard that Madsen could sell 28 guns to Finland after all. The requirement was that, officially, Sweden should be the buyer. The only obstacle now present was the information that Madsen couldn't provide any ammunition for the guns. In February, a message arrived from London that a Kynoch-corporation could produce 20 mm Madsen ammunition, and so, at last a deal could be made.

The 20 mm Madsen on a 2-wheeled towed carriage, in transport position, the drum clip is clearly visible in this picture

28 guns were ordered, and from these 19 arrived that same month (the rest arrived during the following summer). Finnish industrial installations ordered 10 guns, and through their channels some guns were given as a gift. The Danish voluntary unit brought 10 guns with them. More guns were ordered, and while in its peak (September 1943) there were 211 guns in Finland, as far as I know, the number of 20 mm Madsen that arrived to Finland during the war was some 30 guns.

This air-cooled gun could fire both single shots, or automatic fire. The gun was supplied with 4 different mounts. A naval mount, a 2-wheeled towed carriage, a general-purpose tripod and about 20 low silhouette wheeled AT-carriages. Note that the wheeled AT-carriages arrived only after the war.

As the need for AT weapons was so overwhelming, some guns were attached to sledges, and used as AT-weapons. The result wasn't a very good or efficient AT-weapon, but it was better than nothing.

 

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CHARACTERISTICS OF 20 PstK/40

Caliber:
Barrel length:
Overall length:
Weight in firing position:
Gun weight:
Cyclic rate:
Feed device:
Muzzle velocity:

20.1 mm
1 200 mm
2 500 mm
160 kg
app. 53 kg
350 r.p.m.
15-round drum
730-890 m/s

 

Penetration

During the Finnish firing tests, that were made during the war, the following penetration was recorded by the
"20 psav-vj" AP-shot ("-vj" means tracer) with the muzzle velocity of 775 m/s. The armor plate was at an 70° angle.

100 m 200 m 300 m 400 m 500 m 600 m 800 m 1 000 m 1 500 m
25 mm 22 mm 20 mm 18 mm 16 mm 15 mm 11 mm 8 mm 5 mm

Data was kindly provided by Esa Muikku

Note that as no data is available from the armor plate hardness, the performance isn't automatically comparable to the penetration values of other weapons, especially if the used source is different.

 

Back to "Weapons used in Winter War" -page

Back to "Finnish AT-weapons"-page

Go to Part II

 

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Proofread by : Dale Milton, Solomons Maryland USA


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