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Antitank weapons used by the Finns in Winter War

Anti-tank weapons
used by the Finns in the Winter War

Part II


In Part I



Anti-tank rifles



The L-39 from the side
(Note the length of the weapon, the removed muzzle cap and the bipod))

The design and production of a domestic anti-tank rifle for the Finnish Army was delayed in the late 1930s by doubts and differences of opinion over which caliber to adopt. Initially a 13 mm caliber was the favorite alternative but in 1939 a decision was also reached to also construct two 20 mm weapons for tests in mid 1939.

The design work was given to Aimo Lahti who had two 20 mm prototypes produced during the summer. They were then tested. Theoretically, the difference of muzzle velocity and penetration between the 13 mm and 20 mm wasn't big, but the 20 mm round had superior fragmentation effect when it penetrated the armor.

Another frontal view of the L-39
(Note the free traverse once the locking mechanism is opened)

On August 11th 1939, the L-39 performed well, fulfilling all requirements, and on the basis of these superior results the 20 mm weapon was selected and further development of the 13 mm rifle was dropped. On September 6th, 1939, General Heinrichs finally proposed that the production of this good weapon should start immediately.

Before the production of the weapon was started, the Winter War broke out, as the Soviet Red Army attacked on November 30th, 1939. The two L-39 prototypes were first used on the Isthmus front*, near the Lake Ladoga. The weapons were issued to the AT-platoon of JR 28, and the platoon was subordinate to Os.Metsäpirtti (detachment Metsäpirtti), which was part of the delaying / covering troops of the Rautu (R-) group. The two prototype weapons were used with great success against the light Soviet tanks, and the weapon was reported to be effective at ranges of up to 400 metres.

* = Source "Marskin Panssarintuhoajat" by E.Käkelä.   Some other sources say that they were used in Ladoga Karelia


2 men were required to carry this weapon off road. During winter, a sledge was used, and on road marches a vehicle was used if available.


After the Winter War

Later on, the L-39 received improvements e.g. night sights, AA-sights and a targeting scope.

In the attack phase in 1941 the 20 mm round proved to be too weak against most types of tanks. As the L-39 proved to be a very accurate weapon it was often used to destroy enemy gun positions, mg-nests etc. at long range.
Beginning on 1944, the L-39 was also used against the armored ground attack planes. A new pillar mount was designed and the rifle was fitted with extra recoil spring and a fixed striker for full automatic operation. This full automatic AA-weapon was designated as L-39/44.

The 20 mm L-39 from the front



System of operation:
Overall length:
Barrel length:
Feed device:
Sights, Front:
Sights, Rear:
Max ROF:
Practical ROF:
Muzzle velocity:
Max (theoretical) range:

20 mm
Gas-action, semi-automatic
2 240 mm ( 88.2 in )
1 300 mm ( 51.2 in )
49.5 kg ( 109 lbs. )
10-round box magazine
30 r.p.m.
15 r.p.m.
800 m/s ( 2624 f.p.s. )
6.5 km

The weight of the AP ball-cartridge was 337 g, of which the AP-bullet weighted 152 g


When the armor plate was at a 60° angle

300 m 500 m 1 000 m
Weapon manual 20 mm 16 mm 12 mm
Test firing in 1943 20 mm 15 mm 9 mm

(Table source: "Marskin panssarintuhoojat", p.110)

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 0.55 inch "Boys" AT-rifle)

The British 0,55 inch Boys antitank rifle
(Picture source:"Sotilaskäsiaseet Suomessa 1918 - 1988 osa 3", p.267)

This weapon was developed in Britain, in the mid 30s. The weapon was named "Boys" after one of its chief designers, Capt. Boys (deceased just before the production started). It was manufactured by Royal Small Arms Factory Enfield, and it's original designation was "0.55 inch Boys Anti Tank Rifle Mark 1".

100 of these weapons were donated by the British government after the Winter War had begun. They arrived in January, and were immediately distributed to the troops. A second batch of 100 weapons arrived only after the war had already ended.

From the 100 rifles that saw service, 30 were issued to the Swedish voluntary troops (SFK, Svenska Frivilligkåren), as was wished by the British government. The actual combat losses during the Winter War was 6 rifles. Many others were discarded as damaged or other reasons (in June 1940, 178 rifles were left).


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Overall length:
Barrel length:
Feed device:
Muzzle velocity:

13.97  mm
1 614 mm
915 mm
16.6 kg
5 round box
990 m/s

While the caliber of the weapon was quite small, the gun was said to be adequately effective against the T-26 tanks, and lighter vehicles. Of course, the requirement was that you should hit the "soft" points of the tank.

The AP-projectile (bullet) weighed 48 g

When the armor at a 60° angle
(according to Mr.Honner's site, the muzzle velocity was 908 m/s)

91 m 457 m
15 mm 12.5 mm

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


During the Finnish firing tests, that were made during the war, the following penetration was recorded by the
"14.00 psl"("AP-bullet), with the muzzle velocity of 750 m/s. The armor plate was at a 70° angle.

100 m 200 m 300 m 400 m 500 m 600 m 800 m 1 000 m 1 500 m
18 mm 16 mm 14 mm 13 mm 12 mm 11 mm 8 mm 6 mm 4 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.

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THE 13 mm (13.2 mm) AT-MACHINE GUN L-35/36

The 13 mm antitank machine gun on a wheeled carriage
(Picture source: "Marskin Panssarintuhoojat", p.107)

At the same time, when the 37 mm Bofors AT-gun was chosen as the primary AT-weapon, a decision was made to choose the 13 mm heavy machine gun (mg) as the secondary weapon for the frontline troops. While many central European countries like Germany and France decided to have only one AT-weapon, the Finnish terrain (relatively few roads and short firing ranges) also required also a lighter (and cheaper) weapon for the infantry. The State Rifle Factory ("Valtion Kivääritehdas") received the order to design and manufacture a 13 mm mg.

The new weapon was to have several requirements;
1) a high rate of fire, enabling the gunner to score at least a few shots on an attacking tank
2) the weapon was to be accurate
3) and switching targets was to be fast.

One of the reasons why the production of the "secondary" AT-weapon was delayed was the so-called "Calibre squabble"("Kaliipeririita" in Finnish), a public debate between two Army officers, (then) Major Y.A.Järvinen who opted for a 20 mm weapon, and Captain M.Terä, who supported the production of the already chosen 13 mm AT-mg.

No serious resource allocations were made to produce a prototype, so it took until 1938 to produce the first prototypes. The designer for the gun was the well known Aimo Lahti.

A total of 6 AT-mg prototypes were produced, of which one was a semi-automatic version. In addition one mg was manufactured for the lone Landsverk armored car, alongside with two different AA-version prototypes (one single barreled and one 2-barreled).

A wheeled carriage was designed, on which the weapon could be pulled or pushed. The AT-mg could be disassembled into 4 parts, enabling the infantry to carry them. It was possible to remove the gun from the carriage, and converting the weapon into a semiautomatic AT-rifle by attaching a bipod and a butt. The weight of this AT-rifle was 35 kg, making it heavy compared to the AP-performance.

The 13,2 mm L-35/36 used in the Landsverk armored car
(Picture source: "Marskin Panssarintuhoojat", p.105)

The weapon was finally tested against its rival, the 20 mm L-39, which was ironically also A.Lahti's design, and the L-39 was a clear winner. The 13 mm weapon never went into production, and only 3 weapons saw service in the Winter War. One as the main weapon of the Landsverk armored car, one as a single barreled AA-mg, and one in its designed role as an AT-mg in the Taipale sector in the Karelian Isthmus.

The weapon was a failure in its AT-role. The previous weapon tests had been made in the summer, so the weapon's tendency to freeze was unnoticed. The battle experience showed that the weapon wasn't suited for AT-role. It was said that "even from a 30 m range, the weapon couldn't penetrate the armor of a T-26 tank no matter where it was hit, plus the weapon was always out of order".


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System of operation:
Overall length:
Barrel length:
Feed device:
Cyclic rate:
Muzzle velocity:
Max range:
13.2 mm
? (arm. car version, some 1.8 m)
70 - 75 kg
15-round metal belt (arm. car version, 20 round clip)
500 r.p.m.
1 000 m/s (arm. car version some 950 m/s)
5.4 km

The weight of the AP-cartridge was 160 g, of which the projectile weighed 50 g.


When the armor was at an 60° angle.

300 m 500 m 1 000 m
Weapon manual 22 mm 18 mm 12 mm
Test firings in 1939 15 mm 13 mm 7 mm

(Table source: "Marskin panssarintuhoojat", p.105)

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.

But the armor hardness was probably quite low, when comparing the above figures to the feedback from the actual users.

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A Molotov Cocktail on a soldier's belt
Picture source:
"Talvisodan Historia 2", p.60

The "official" design of a Molotov Cocktail

While the Molotov Cocktail was first used as a weapon in the Spanish civil war, the "poor man's AT-weapon" was baptized as the "Molotov Cocktail" in the Winter War. Even today it's a common weapon of terrorists and rioters, because it's easy to manufacture and to use.

The Molotov Cocktail, that was used by the Finns in the Winter War was developed by a design team, led by Captain Eero Kuittinen, commander of the Er.PionK (the peace time separate Pioneer company).

In 1939, a "Pioneer Technical Manual, no.1" was printed in Viipuri, and according to it, a 1/2 liter liquor bottle with a screw cap was ideal for making this type of a weapon. As the flammable liquid, petrol, spirit, a mixture of petrol and kerosene or a mixture of waste spirit and kerosene, could be used. The manual advised 1-2 cubic centimeters of tar to be added, to create smoke.

Different kinds of molotoc cocktailsPicture on the left was taken in the Armour Museum in Parola, Finland

On the left are three diffent kinds of "Molotov Cocktails". The bottle on the left is an empty liquor bottle (the text "VIINAA" means booze), and it has a piece of cloth tied around the bottle's neck. The bottle in the center is a bit "improved", but still very crude, and finally on the right is a factory-produced version.


For making the weapon, the manual instructed: "After the bottle has been filled with the liquid, the screw cap is properly closed and sealed with an insulating tape. On the opposite sides of the bottle, straps of cloth or insulating tape is to be attached, to prevent the heat of the "Bengal match" (a sort of a big match, that didn't go out easily, also known as "myrskytikku" in Finnish) from breaking the glass. Both matches, with their insulating tapes, were fastened on two points by more insulating tape (see the example on the left) and wire used to strengthen the result.

A Molotov Cocktail
Picture source:
p. 314

In Finland, as the lack of AT-weapons was appalling, the industrial production of Molotov Cocktails was quick to start. The production began in the State Liquor factory in Rajamäki, and while the early models had mostly petrol, the mixture was soon changed into the following:

60 % of Potassium Chlorate
32 % of Coal tar
8% of Noulee

A total of 542 194 Molotov Cocktails were produced between December and March, produced by a work force of 87 women and 5 men.

The late production Molotov Cocktails had, as it's incendiary device a small sulfuric acid capsule in the bottom of the bottle. This removed the need for the AT-man to pre-ignite the bottle, as the ignition medium was lit upon the bottles breaking.


Before the war, the Molotov Cocktail was seen more as a weapon that would blind or suppress the target tank, making it easier to destroy it by other Molotov Cocktails or by satchel charges. The idea of breaking the bottle on the rear end of the tank (where the engine compartment was located), near the ventilation, wasn't yet realized, but that changed quickly after the war started. The hot engine (the Soviet engines at that time were gasoline engines) of the tank caught fire quite easily, making this weapon quite effective against the tanks of early WW 2.

Late in the war, the Soviet tankers attached bushes or wire mesh to protect the rear end of the tank (hoping that the bottle wouldn't break, as it wouldn't hit the armor), but the Finnish solution was to tie 2 - 3 stones at the end of strings and tying the strings on the bottle so that the stones would shatter the glass. Also barbwire was wrapped around the bottle, so that if the bottle hit the mesh protecting the ventilation, the chance of setting the engine on fire increased.



("Kasapanos" in Finnish)

The factory manufactured 3 kg satchel charge
The factory manufactured 4 kg satchel charge

In 1936, Captain Kaarlo Tuurna, serving in the Pioneer battalion, developed the Finnish kasapanos. In tests it was noticed that 0.5 kg of TNT could break 12 mm of armor if pressed tightly against the armor plate. Thus it was concluded that a kasapanos with 0.8 kg of TNT was sufficient. This was of course an insufficient explosive charge for WW 2 tanks, but at least the basic design and requirements of the weapon were set.

Although the industrial production of satchel charges had been started before the war, the design was developed further during the war. The factory produced satchel charges (see examples left and right), were made in 2 kg, 3 kg and 4 kg versions. The explosives were in a box covered by sheet metal, while the wooden handle and fuse were those of the stick hand grenade (German m/32 hand grenade, the "potato smasher").

A satchel charge made by the troops, TNT attached to a stick handgrenade
Picture was taken in the
Armour Museum in
Parola, Finland
A factory produced "kasapanos"
Picture source:
p. 314

The early models of the factory produced satchel charges had both of the larger sides coated by special glue in order to decrease the chance that the satchel charge would fall off from top of the rear deck of the tank. The glued sides were protected by plywood, which was removed only moments before the throw. The glued satchel charge wasn't a success, as the glue clung easily to the clothes (gloves etc.) of the user.  If the glue was touched by snow or dirt, the effectiveness of the glue was reduced considerably.

The late production satchel charges had small hooks on each side of the explosives container box, on the "upper" edge (if holding the satchel charge in hand, see example on the left). The hooks were intended to clung the charge on the tank (if lucky), e.g. to the wiring net covering the engine ventilation. A more often used method to increase the chance of getting the satchel charge to stay on top of a tank was to attach barbed wire around the explosives, which clung on more easily.


A "self made" kasapanos, being finished on the front
Picture source:
"Talvisodan Historia 2", p.60

Of course, the factory produced satchel charges weren't the only ones used. The troops made ones themselves, and in fact, Finns called nearly all sorts of explosive bundles as "kasapanos". One simple (and one of the most widely used) method was to tie the explosives on a piece of wood (see the picture on the right), and ignited by a priming wire.


Effectiveness of the "kasapanos"

It was quickly noted that a 1 - 2 kg charge was sufficient for severing the track of a tank, if blown under or next to the track.
  A satchel charge with 6 kg of explosives, built around a stick hand grenade, was powerful enough to knock out any tank met in the war, if it exploded on top the tank (usually on the rear deck of a tank).

In a notice, issued on February 1940, to the ground troops by the Chief of Engineering section of the Finnish General HQ, the effectiveness of various explosive charges was reported to be as follows:

  • 2 kg was sufficient to destroy vehicles with the weight of around 6 tons
    (FAI, BA-3, BA-6, BA-10, T-37, T-38)
  • 3 kg was sufficient to destroy vehicles with the weight of around 12 tons
    (T-26, BT-2, BT-7)
  • 4 kg was sufficient to destroy vehicles with the weight of around 30 tons

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In 1932, the Finnish General Staff set the requirements for an AT-mine, which was the starting shot for the use of AT-mines in the Finnish military. The start was difficult, and therefore a committee led by Lt.Col K.Pylkkänen was formed, and in 1936, an AT-mine designed by the committee was approved by the Army. The design (the m/36) was mainly the handwriting of a committee member Lt.Col T.Raatikainen.

The Ordnance section of the Defense Ministry developed the design of the m/36 further, and the more powerful design (the m/39) was accepted in 1939. While it was was very easy and quick to build a mine barrier with m/36 mines, the m/36 and m/39 were kept under tight secrecy (even from career soldiers) well until 1938, which caused the mine model with its relatively complicated fuse to be quite unknown among the reservist pioneers.

As the casing material of both of the previous mine types was iron, and both types were difficult to produce, a mine with a simple construction and a wooden casing was introduced (the m/S-39).

As the mobilization ("extra rehearsal", "YH" in Finnish) started, the total number of AT-mines was only 5 000 (4 825 mines were given to the troops in the Karelian Isthmus, while the troops defending the rest of the border received only 175 mines), all of which were m/36. The production of m/39 hadn't even begun yet. Between Nov 10th and 26th, the Army received only 2 157 new AT-mines. The shortage of factory produced AT-mines, and the complete absence of factory produced anti-personnel mines, forced the troops to build most of the mines and booby-traps themselves. One self made AT-mine was a piece of log that was split in two, carved hollow and filled with explosives.

Of course, guidelines and instructions for this were available for the troops. The troops had app. 10 000 percussion fuses, 10 000 friction fuses, 300 000 blasting caps with priming wire, 150 000 electric caps, 35 000 m of exploding priming wire (blasting cable?), 150 000 m of priming wire and some 226 tons of explosives.

During the war, thousands of AT-mines were bought from abroad, e.g. some 60 000 from Britain alone.


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AT-mine m/36

Total weight: 5.5 kg
Explosives weight: 2.8 kg
Height: 13 cm
Base width: 31 cm
Cover width: 26 cm

The mine had a cast iron casing, and the fuse required a weight of 350 kg, to detonate the mine. The first fuse design wasn't satisfactory, as it was judged to be too complicated (a new fuse type wasn't developed until after the Winter War). Also the explosive charge was considered too small.

The toothing of the base plate made it difficult to use the mine daisy chained, where a rope is fastened to a mine (or several mines), and pulled on the last minute under the track to ensure a "hit".

1. cap of the detonator ("kansitulppa" in Finnish)
2. spring ("jousi")
3. cover plate ("painokansi)
4. pitch gasket ("pikitiiviste")
5. explosive container ("räjähdysainesäiliö")
6. handle ("sanka")
7. explosive ("räjähdysaine")
8. fuse ("sytytin")

The M/36 AT-mine
Picture was taken in the Armour Museum in Parola, Finland

A schematic display of the M/36 mine
(Source: "Marskin panssarintuhoojat", p.52)

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AT-mine m/39

Total weight: 7 kg
Explosives weight: 3.2 - 3.5 kg
Height: 12 cm
Width: 23 cm

The mine had an iron casing, the strength of the explosion could be increased by adding an extra 2.5 kg of TNT below the mine.

1. cap of the detonator ("kansitulppa" in Finnish)
2. cover plate ("painokansi")
3. spring ("jousi")
4. pitch gasket ("pikitiiviste")
5. hoop ("vanne")
6. explosive container ("räjähdysainesäiliö")
7. plywood box ("vanerirasia")
8. detonator tube ("räjäyttimen putki")
9. detonator ("räjäytin")
10. fuse ("sytytin")
11. explosive ("räjähdyspanos")

a bit rusty m/39 AT-mine
Picture was taken in the Armour Museum in Parola, FinlandA schematic display of the M/39 mine
(Source: "Marskin panssarintuhoojat", p.95)

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AT-mine m/S-39

Total weight: 6.5 - 7.5 kg
Explosives weight: 3 - 3.8 kg

As iron become more expensive and as the iron casing was relatively hard to produce, a mine with a wood casing was designed.

The wooden casing reduced production costs, and made it easy to manufacture.

The new wood cased mine m/S-39
(Picture source: "Talvisodan Historia 1", p.175)



The 37 mm Infantry Guns

37 K/14 and 37 K/15

The 37 K/14 on the left and 37 K/15 on the right


The acute shortage of antitank weapons forced the Finnish Army to use quite desperate tools in an effort to increase antitank capability. One of these efforts was the use of old WW1 vintage infantry guns in an antitank role.

Finland had 14 old infantry guns, the 37 mm Infantry Gun Model 1914 (made by Obuhoff) and 37 mm Infantry Gun Model 1915 (made by Rosenberg). Both were (as far as I know) Russian built during the WW1 and captured by the Finns during the War of Independence.

In order to make statistics more pretty, these type of guns were listed as 37 mm AT-guns with the 37 PstK/36 (Bofors). Some were even sent before the war to front-line units, such as the 15th Infantry Regiment (JR 15) of the 5th Division, defending in the Summa sector. The JR 15 had in early November received a two gun platoon of 37 mm Bofors guns. Around mid-November it received two platoons of 37 mm Infantry Guns (five 37 K/15 guns each), and combined them into an antitank company.

As both guns were able to defeat only 10 mm of armor (if the plate was vertical, i.e. 90 degree angle) from a range of 200 meters, using a solid steel shot, all guns of this type were quietly withdrawn from the front-line after the first engagements, as totally useless weapons.



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Proof-read by: Dale Milton, Solomons Maryland USA

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