ANTITANK GUNS PART 1:

20 mm - 37 mm Guns

 

20 PstK/40 Madsen

(20 mm antitank gun M/40 Madsen)

PICTURE: 20 mm Madsen automatic gun with antitank mount. (Photo taken in Jalkaväkimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (50 KB).

Calibre:

20 mm x 120 Madsen

Length:

250 cm

Barrel length:

120 cm aka L/60

Weight in action:

160 kg (with AT-mount used)

Rate of fire:

350/min (theoretical) / 200 - 250/min (practical)

Muzzle velocity:

Theoretical: 730 - 890 m/sec

in reality: 690 - 780 m/sec

Magazine:

15 (box), 40 (drum) and 60 (drum) (*)

Width:

110 cm

Height:

80 cm

Country of origin:

Denmark

Ammunition types:

AP-T, APHE, HE-T, HE

(*) 40-round drum was the original magazine for this weapon. Madsen factory delivered also later introduced 60-round drums to Finland with model 1940 variation of the Madsen-gun during World War and 15-round box magazines were likely also used at least during Winter War. All of these magazines were removable.

Armour Penetration:

- Results of Finnish test firing in 1941:

- "Guns vs Armour website" by D.M. Honner (likely 158-gram AP-T projectile "20 psav - Vj5", 775 m/sec, 5-second tracer):

- Finnish live fire testing year 1943 ("20 psav-Vj" AP-T, 775 m/sec):

Finnish use: 20-mm Madsen automatic guns were mostly used as AA-gun in Finland. During Winter War few used as AT-guns with improvised sledge mounts. Later during early part of Continuation War small number with antitank / ground support gun carriages (one-axle wheeled mount) guns were used as antitank-guns. By March of 1942 all of these guns of antitank-gun version had been transferred to coastal troops.

This automatic cannon was developed in Madsen factory in Denmark and become commercial success in 1930's. It was selective fire recoil action automatic gun capable both to semiautomatic and full automatic fire. Weapon had several mount options, from these the one axle model with rubber tires was the most suitable for antitank use. Madsen gun was popular in many roles, from these the antiaircraft use was the most popular, but they were also used as armaments of aircraft and armour vehicles. Among countries using 20-mm Madsen gun before or during WW2 were Denmark, Sweden, Finland, Norway, Estonia, Czechoslovakia, Poland, Belgium, France and Germany.

PICTURE: 20 mm Madsen automatic gun with antitank mount seen from another direction. (Photo taken in Jalkaväkimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (41 KB).

The Finns had been aware and interested of 20-mm Madsen from the start. Year 1929 Aimo Lahti and Major Söderberg had participated to its test shooting. They discovered that weapon was otherwise good, but was somewhat picky when it come to ammunition - ammunition used in tests was not as precisely manufactured as it should have been and caused malfunctions. Finnish Navy has bought few 20-mm automatic cannons with column mounts for AA-use just before Winter War, but only starting of Winter War made Finland to start buying Madsen automatic guns in large numbers. During Winter War the Danes became afraid of German reaction if they would sell weapons to Finland and getting ammunition was difficult also early on. However both of these problems were solved, Finnish purchases of Madsen were disguised as Swedish ones and Kynoch Corporation delivered ammunition needed for them to Finland.

First Madsen guns were delivered to Finland in February of 1940. Only about 30 guns or so arrived to Finland during Winter War and all of these came with mounts designed to antiaircraft use. As the Finns had extremely serious shortage of antitank guns the idea of using Madsen automatic guns in that use appeared, but as the shortage of AA-guns was equally dire also getting them for that use was no easy. During last weeks of Winter War some of the Madsen guns installed to improvised sledge mounts saw some action as antitank guns.

Most of 20-mm Madsen arrived during Interim Peace between Winter War and Continuation War and their amount peaked to 211 in autumn of 1943. Only about 20 or so were with antitank mount. When Continuation War started they were issued to Finnish frontline troops until being withdrawn from use early 1942 (by March). After that they were issued to coastal troops and remained in their use until end of World War 2. Both rate of fire and accuracy of Madsen guns were very good, but their armour penetration capability left a lot to desire. Starting from year 1941 20 mm x 120 Madsen ammunition was manufactured domestically by Tikkakoski, who made both AP-T and HE/HE-T ammunition in this calibre. Around the same time also Oy Ammus manufactured small amount of AP-T ammunition for Madsen guns. Officially the last 20-mm Madsen guns were not removed for use of Finnish Armed Forces until 1986.

 

25 PstK/34 and PstK/37 "Marianne"

(25 mm antitank guns M/34 and M/37 "Marianne")

PICTURE: 25 mm antitank gun M/34. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (27 KB).

Calibre:

25 mm x 194 R

Length:

392 cm (PstK/34)

Barrel length:

180 cm (PstK/34) / 181 cm (PstK/37) aka L/77

Weight in action:

496 kg (PstK/34) / 310 kg (PstK/37)

Rate of fire:

?

Muzzle velocity:

918 m/sec (PstK/34) / 900 m/sec (PstK/37)

Magazine:

None

Traverse:

37 degrees

Elevation:

-10 degrees, +25 degrees

Max. range:

1800 m (presumably direct fire)

Width:

105 cm (PstK/34)

Height:

109 cm (PstK/34)

Country of origin:

France

Ammunition types:

AP-T, AP (projectile 320 g, 750 m/sec)

Armour Penetration:

- "Guns vs Armour website" by D.M. Honner (AP-T, 920 m/sec):

Finnish use: Less than 40 used by Finnish troops in frontline use during last few weeks of Winter War. Another 200 bought during Interim Peace and used in frontline use during Continuation War until being replaced by more effective at-guns by mid 1942.

French M/34 antitank gun was product of Hotchkiss factory and developed in early 1930's. Its later designed competitor M/37 antitank gun was mainly manufactured by Puteaux factory. Both guns has same ballistics and same basic structure, in fact the largest main difference between the two was weight, which favoured M/37. Largest notable visible differences between the two are the structure of gun shield and wheels. Both guns used same ammunition. During German attack to France in 1940 these guns were the main antitank-gun types used by French Army. They proved to be accurate guns, and flash-hiders used in them made them quite difficult to spot, but their armour penetration capability and range were not good. The Germans captured both guns in large numbers in 1940 and used them in secondary roles as coastal defence and in some garrisons. Only ammunition types Finnish military used with these guns in battle were AP (armour piercing) and AP with tracer. This made them only antitank-guns in Finnish use without HE-ammunition (HE = high explosive). Anyway this was not much a shortcoming, because while high-explosive rounds are useful against enemy infantry and other soft targets, the 25-mm calibre was too small to make much of a difference. When each individual round had to be manually loaded to the gun the effect of resulting rate of fire combined with small 25-mm projectile probably just wasn't considered worthy for developing high-explosive round.

PICTURE: 25 mm antitank gun M/34. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (29 KB).

Finland purchased 50 French 25-mm M/37 antitank guns during Winter War, but only 40 of them were delivered in February of 1940 through Norway. The remaining ten guns were captured by the Germans when they invaded Norway in spring of 1940. About half of the guns, which had arrived during Winter War saw frontline service during it and three of them were lost in battle. During Interim Peace the Germans offered Finland another 200 French 25-mm antitank guns that they had captured. This shipment arrived from Germany 10th of December of 1940 with S/S Hohenhörn and included:

  • 133 antitank guns M/34
  • 67 antitank guns M/37
  • PICTURE: Closer look to systems of 25 mm antitank gun M/34. Note breech system with vertical sliding breech block and optical sight. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (41 KB).

    When Continuation War started large number of 25-mm guns were issued to Finnish frontline troops, but soon their weak armour penetration capability made them outdated, so withdrawing them from frontline use started already early 1942. Report concerning antitank-guns used by Finnish Army dated February 1942 notes from these guns that: "Their armour-penetration capability is such, that they have no meaning as actual antitank-weapons..." The last of 25-mm antitank-guns were withdrawn from frontline use in year 1943. After the war they were kept warehoused until being declared obsolete in 1959. The remaining 225 guns were sold to Interarmco in 1960.

     

    37 PstK/36 Bofors

    (37 mm antitank gun M/36 Bofors)

    PICTURE: Swedish made 37 mm Bofors antitank gun. Notice the "waved" sides of gun shield used to make spotting the gun more difficult. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (39 KB).

    Calibre:

    37 mm x 257 R

    Length:

    304 cm

    Barrel length:

    174 cm (with muzzle brake) aka L/45

    Weight in action:

    375 kg

    Rate of fire:

    30 shots/min (maximum) / 12 shots/min (practical)

    Muzzle velocity:

    500 - 810 m/sec

    Magazine:

    None

    Traverse:

    26 degrees

    Elevation:

    -10 degrees, +25 degrees

    Max. range:

    7400 m (indirect fire) / 4500 m (direct fire)

    Width:

    109 cm

    Height:

    103 cm

    Country of origin:

    Sweden, manufactured also in Finland and Poland

    Ammunition types:

    AP-T, APHE, APHE-T, HE-T, HE, phosphorous (rare)

    Armour Penetration:

    - "Marskin panssarintuhoojat" (870 m/sec):

    - Finnish live fire testing year 1943 ("37 psav - Vj4", AP-T, 810 m/sec):

    Finnish use: This was the first purpose-build antitank-gun in Finnish use, but only 48 guns had arrived before Winter War. Another 66 guns imported from Sweden during Winter War, 10 Polish guns imported during Interim Peace and 355 guns from Finnish license production made it most typical at-gun in Finnish use during Winter War and early Continuation War. They were first transferred to other duties than antitank use and ultimately removed from frontline use by early 1944.

    Prototype of this light but effective (according standards of that time) antitank-gun was finished in year 1932. Its first version was named M/34 after the year it become ready to production. First country to order it was (delivery of 12 guns) was Netherlands in 1935. The Swedes themselves bought the first guns of this type in 1937 and called them 37 mm pkan M/34. During production new versions called M/38 was developed and replaced the old M/34 version in production. 37-mm Bofors at-gun was worthy competitor to German 3.7 cm Pak 35/36 in every category in late 1930's, so it achieved some commercial success. Among countries to which it was imported were Denmark, Finland, Great Britain, Poland, Turkey and Yugoslavia. Poland also acquired production license for these guns in 1936 and manufactured them under name Armata przeciw-panzerna wz. 36. German troops captured reasonably large number of 37-mm Bofors at-guns in Poland in year 1939 and renamed them as 3,7 cm Pak 36(p) before issuing them to their own troops. It is believed some of those guns in German use saw action against British troops in North Africa, where incidentally also British used their 37-mm Bofors at-guns. The main differences between Finnish, Polish and Swedish made guns of this type are in sides of gun shield (straight or "waved") and in wheel structure.

    PICTURE: Another pic of Swedish made 37 mm Bofors antitank gun. Notice the "OHOHOHOH..." pattern in tires, typically tires with this pattern were used in Finnish and Swedish made 37 PstK/36 guns, while usual tire pattern of Polish made guns had the "razorback"-pattern. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (34 KB).

    PICTURE: More closer look to systems of Swedish made 37 mm Bofors at-gun. Note original Swedish sight in left side of breech and semi-automatic breech mechanism using vertical sliding breech block. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (65 KB).

    Finland accepted 37 mm Bofors M/36 as new main at-gun October of 1938 from Bofors and order was made still in that same year. October of 1939 another batch of 24 guns were ordered and in January of 1940 yet another batch of 18 guns was ordered. Before Winter War Finland had received 48 guns of this type, during Winter War another 66 guns were delivered from Sweden (guns used by Swedish SFK voluntary force not included to these numbers). 37-mm Bofors at-guns bought from Bofors to Finland included both M/34 and M/38 versions. December of 1939 Finns also bought 20 Polish-made 37-mm K/36 at-guns from Hungary, but Germans managed to delay their delivery until summer of 1940.

    While none of the Finnish books or articles mention this some documents in Military Archives claim that additional 22 guns were ordered from Germany after Winter War. Presumably these 22 guns would have been delivered in August of 1941. If they were delivered they were likely Polish origin.

    PICTURE: One of the 20 Polish made 37 mm Bofors antitank guns in Finnish use. Notice the straight sides of gun shield and "razorback" tire pattern. (Photo taken in Panssarimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (53 KB).

    Finland also acquired license for production and two Finnish companies, Tampella and VTT (Valtion Tykkitehdas = State Artillery Factory) manufactured these guns. The two companies could have hardly been more different, but both were still newcomers when it came to manufacturing weaponry. Tampella was old privately owned limited liability company, whose Weapons Department established 1932 had before this been focused manufacturing mortars. In addition of manufacturing Brandt-Stokes mortars under license (also as sub-contractor of Brandt-Stokes) it had also developed its mortar designs. VTT (State Artillery Factory) was state-owned company established just February 1939 as manufacturing plant of heavy weapons for Finnish Armed Forces. Other factories, which played important role in manufacturing 37 PstK/36 in Finland were Lokomo and Crichton-Vulcan. As usual Lokomo Works was the manufacturer that supplied both Tampella and VTT the needed barrel blanks. Crichton-Vulcan manufactured parts made from heavy steel plates - mainly gun shield and most large parts needed for gun carriage. First Finnish-made guns rolled out of factories in summer of 1939.

    Before start of Winter War the following number of 37 PstK/36 was manufactured:

    Manufacturer

    Amount

    Tampella

    48

    VTT

    32

    By end of 1939 Tampella and VTT had manufactured (the earlier amounts included):

    Manufacturer

    Amount

    Tampella

    48

    VTT

    48

    Finnish plan (from year 1938) had been originally to provide antitank-gun platoon with 2 antitank-guns to each "field battalion" (battalion of infantry, at the time each Finnish infantry regiment had three of these battalions), but when Winter War started Finland was not even close of having the amount of antitank-guns needed for this. When Winter War begun in 30th of November 1939 Finnish Army had only 98 Bofors at-guns, while having 9 divisions and each of them typically having 10 "field battalions" (9 infantry battalions and one light battalion per division). So obviously the number of existing antitank-guns didn't allow following that plan. What resulted then was an improvised solution, which didn't really follow any pre-war plan. Antitank-gun platoons existing when the war begun went to frontline with the units, to which they belonged. When more guns became available new antitank-gun platoons were hastily equipped and trained in Antitank-gun Training Centre (Panssarintorjuntakeskus) located to town of Hämeenlinna. After receiving training of less than two weeks these new platoons were sent to frontlines and issued to various units. Shortage of antitank-rifles demanded the Finns to use their antitank-guns (also very limited in number) in immediate front-line during Winter War and this lead to high losses. By end of Winter War Finnish troops had received 222 guns of this type (this includes both guns acquired from Sweden and Finnish production), but at the same time about 60 of them had been lost in battle. So the number of guns didn't really increase very much during Winter War. 37 PstK/36 antitank-guns were suitable both for motorised towing and being towed by horses (the gun was so light that only one horse was needed for towing it, but limber had to be used with a horse).

    PICTURE: Finnish made 37 PstK/36. Notice streight sides of gun shield and tire pattern, which were typical to Finnish and early Swedish made guns. (Photo taken in Maneesi of Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (46 KB).

    When the Germans invaded Denmark and Norway in April of 1940, it quickly made Swedes to realise how dangerous their situation actually was. Sweden started to mobilise fast and asked some of the weapons it had delivered to Finland to be returned. Among weapons that Finland returned also were 20 Swedish 37-mm Bofors at-guns of Swedish manufacture. These 20 guns returned to Sweden included 7 guns that had arrived with Swedish-Norwegian SFK volunteer unit and 13 Finnish-manufactured guns, which Swedish Army named M/38 F. May of 1940 only 25 of the 114 guns delivered to Finland from Sweden still remained in Finnish use.

    The Finns also were having ammunition shortage with 37-mm Bofors antitank-guns during Winter War, only 32,000 shells had been bought for these guns before the war. This soon proved to be much too little and further Swedish ammunition deliveries were not fast or large enough to remove the problem. To fix the situation domestic ammunition production was started in VTT (Valtion Tykkitehdas = State Artillery Factory) in December of 1939. But the production in VTT started slowly (only 1,680 shots made in December 1939) and the 18,000 shots it managed to make during Winter War failed solving the ammunition-shortage. During Winter War Finnish military ordered ammunition for these guns from Sweden almost on daily bases. Finnish domestic ammunition production finally ended the ammunition shortage of these guns in year 1941. From that on Finnish military had plenty of ammunition for them.

    Finnish military used variety of sights with 37 PstK/36 antitank-guns. Most if not all Swedish-made guns were delivered with Swedish optical sights and some have later been spotted in Finland also with German-made (Oigee and Carl Zeiss) optical sights. These German-made optical sights may have originally belonged to Finnish-made, acquired later for them or even arrived with the Swedish or Polish-made guns. Acquiring suitable sights for guns manufactured in Finland with license proved problematic early on, so at least three kind of Finnish sights were used with them. The first "emergency-sight" seems to have been simple contraption, in which sights of rifle M/28-30 have been attached to piece of rifle barrel about 30-cm (12 inch) long. The second Finnish-made sight model used with these guns was also rather simple collimator sight. The third version was also collimator sight, which Tampella seems to have manufactured early 1940. What is known there were also Polish-made optical sights arriving with Polish-made guns. It's reasonably certain that Finns succeeded acquiring optical sights for the license-manufactured 37 PstK/36 guns from Germany after Winter War.

    Originally these guns had been designed for motorized towing, in other words they were intended to be towed with trucks. However Finnish military also designed and introduced limber, which allowed the gun to be horse-towed. Only one horse was needed for towing the gun. While the Finnish pre Winter War Antitank-gun Platoons armed with these guns were all motorized, also horse-towed (antitank-gun) platoons started to appear during it and continued to exist also during Continuation War. The maximum towing speed for this gun was only 25 km/hour.

    PICTURE: 37 PstK/36 manufactured by Tampella in year 1940. This particular gun has been painted with Finnish post-WW2 "splinter" camo pattern. One of the two lower armour plates is missing. (Photo taken in Bunkkerimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (147 KB).

    Finnish license production continued until year 1941, deliveries of 37 PstK/36 at-guns manufactured in Finland:

    Manufacturer

    1939

    1940

    1941

    Total

    VTT

    48

    7

    0

    55

    Tampella

    48

    152

    100

    300

    Total

    96

    159

    100

    355

    Notice: According some sources VTT manufactured 8 guns in 1940. In addition to guns listed above VTT manufactured also 33 of 37 Psv.K/36 (tank-gun version of 37 PstK/36 antitank-gun) in 1939 - 1940.

    During Winter War 37-mm Bofors antitank-gun was still powerful enough to knock out any Soviet tanks (only exception being the heavy tanks like KV tested during it) in use at that time. But during Continuation War new Soviet medium and heavy tanks proved to be too thick armoured for at-guns like 37-mm PstK/36. Officially last of these guns were not removed front line use until early 1944, but typically they had not been used as at-weapons for quite some time before that. Around 1942 - 1944 they were mostly used for knocking out Soviet bunkers, machinegun-nests, direct-fire guns etc. With their small weight, high rate of fire and good high-explosive rounds they proved well-suited to this kind of use. Year 1944 their number was still so large (about 250) that Finnish Armed Forces wanted to find new uses for them, so they continued to serve as infantry guns until year 1986.

    Losses of 37 PstK/36 antitank-guns guns during period 9th of June - 7th of July 1944:

    Unit:

    Losses:

    III Army Corps

    11

    IV Army Corps

    9

    V Army Corps

    7

    Aunus Group

    23

    Total:

    50

    Finnish ammunition manuals list following ammunition for 37 PstK/36 antitank-gun and 37 Psv.K/36 tank gun:

  • 37 tkrv-Vj6-27/30 K/36 pr.: TNT-filled HE-tracer round, projectile weight without fuse 725 g, muzzle velocity 815 m/sec.
  • 37 tkrv 27/30-R K/36 pr.: TNT-filled HE round, projectile weight without fuse 575 g, muzzle velocity 830 m/sec.
  • 37 pstkr 27/34-ps R K/36 pr.: TNT-filled APHE round, projectile weight with fuse 740 g, muzzle velocity 810 m/sec.
  • 37 ps R 27/34-Vj6 K/36 pr.: APHE-T version of the previous APHE round, projectile weight with fuse 740 g, muzzle velocity 810 m/sec.
  • 37 pstkr 27/34-ps R K/36 pp.: Another TNT-filled APHE round, projectile weight with fuse 700 g, muzzle velocity 830 m/sec.
  • 37 pstkr 27/34-ps R K/36 pr.: Another TNT-filled APHE-T round, projectile weight with fuse 740 g, muzzle velocity 810 m/sec. Added to ammunition manuals in end of October 1941
  • 37 psav-Vj4 K/36 pr.: AP-T round, projectile weight with fuse 740 g, muzzle velocity 810 m/sec.
  • 37 psav-Vj4K/36 p.: Another AP-T round with shorter projectile, projectile weight with fuse 740 g, muzzle velocity 810 m/sec.
  •  

    37 PstK/37 and PstK/40

    (37 mm antitank guns M/37 and M/40)

    (3.7 cm Pak 35/36)

    PICTURE: 37 PstK/37 antitank gun. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (42 KB).

    Calibre:

    37 mm x 249 R

    Length:

    350 cm

    Barrel length:

    166 cm aka L/45

    Weight in action:

    330 kg / 450 kg (depending source)

    Rate of fire:

    12 - 15/min (practical)

    Muzzle velocity:

    500 - 1030 m/sec

    Magazine:

    None

    Traverse:

    60 degrees

    Elevation:

    - 8 degrees, + 25 degrees

    Max. range:

    6800 m (indirect fire)

    Width:

    160 cm

    Height:

    120 cm

    Country of origin:

    Germany

    Ammunition types:

    APHE (Pzgr.) 680 g projectile 760 m/sec

    (APCR (Pzgr.40) 354 g projectile 1030 m/sec - not in Finnish use)

    HE 690 g projectile 710 m/sec

    Stielgranade 41 HEAT bomb 8500 g 110 m/sec (1942)

    Armour Penetration:

    - "Panzerabwerhgeschütze etc":

    - "Small arms, artillery and special weapons of the third reich":

    - "Twentieth Century Artillery":

    - "Deutsche and alliierte heereswaffen 1939 - 1945":

    - Finnish live fire testing year 1943 ("37 pspekr 22/27-ps", German APHE, 710 m/sec):

    Finnish use: Germans delivered 200 guns in 1940 - 1941 to Finland. With little help from 5,000 Stielgrenade HEAT bombs acquired in 1942 they remained in Finnish use until end of Continuation War, however in 1943 - 1944 large number of these guns were replaced with more heavy-calibre ones.

    Development of 37-mm antitank gun started in Rheinmetall factory in 1925 and first prototypes were tested in 1928. First delivery of 264 horse-towed 3,7-cm at-guns was issued to German Army in 1932, but this early version didn't see large-scale production, as changes were made to guns mount already in 1934. The new very much improved mount and rubber-wheels allowed the new version to be towed with motor vehicles also. Some more changes were introduced to guns little-by-little around 1935 - 1936, these included change in manufacture method of gun barrel, replacing existing equipment boxes with bigger ones and improvements in towing system and tires. 3.7 mm Pak (shorter version from "PanzerAbwerhKanone") as Germans called it was reasonable export success, countries to which it was exported before World War 2 included Soviet Union, China, Italy, Netherlands, Greece and Estonia. Already before World War 2 these guns saw use in Chinese-Japanese war and Spanish Civil War. in the same time German 37-mm at-gun also had large affect to antitank-gun developments of many other countries, especially US 37-mm and Soviet 45-mm at-guns were clearly based to its structure.

    Before starting of World War 2 some 11,200 German 3.7 cm Pak were manufactured and by 1941 the number reached 15,000. French and British heavy tanks which the Germans met first time in France in summer of 1940 were already quite resistant to their fire, but it was the large amounts of T-34 and KV-1 tanks fielded by Soviets that finally proved too much for 3.7 cm Pak to handle. The Germans had made good work with development of ammunition used in this gun introducing tungsten-cored Pzgr.40 APCR-ammunition and large sized Stielgranade 41 HEAT-bomb, but new tanks were too thick-skinned even for Pzgr.40 and short range of Stielgrenade 41 made it basically an emergency weapon with questionable effectiveness. So, production of 3,7 cm Pak ended in March of 1942.

    PICTURE: Closer look to systems of 37 PstK/37 antitank gun. Sight of this gun seems to be missing. Also note breech system with semi-automatic horizontal sliding breech block typical to German at-gun designs. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (51 KB).

    The Finns had been very much aware of German 37-mm antitank-gun already before World War 2, but Bofors gun had been favoured before Winter War and during Winter War Germany in accordance with its agreements with Soviet Union (generally) didn't sell weapons to Finland. However, as soon as the Interim Peace following Winter War started situation changed and first delivery of 50 guns from Germany was made through Hungary. It seems that this first delivery arrived within few weeks after ending of Winter War (in other words: late March - early April 1940) and that the Germans probably tried to secret it from the Soviets. In many Finnish documents the source for these 50 guns have also been marked as Spain. The second delivery batch containing 100 guns arrived from Germany in September of 1940. The third and final delivery batch of 50 guns arrived from Germany in June of 1941.

    The Germans didn't separate different versions of their Rheinmetall 37-mm antitank gun to sub-models, they all were simply called 3,7 cm Pak. The Finns did the other way and divided these guns to two models - PstK/37 and PstK/40. The main factor separating the two gun models in Finnish use was structure of barrel, which had changed when Germans had made changes to ease its manufacturing. Barrel of K/37 had an obvious jump in barrel thickness about middle length of barrel, while in barrel of K/40 the angle of change in barrel thickness was constant in full length of barrel. The Finns bought large numbers of spare parts for these guns - the same spare parts fit to both of these gun models. Due to this the wartime repairs actually changed most of the Finnish Army PstK/37 and PstK/40 guns to mixed versions referred as PstK/37-40 and PstK/40-37. Apparently the guns delivered to Finland were equipped with primary optical sight and collimator-type backup sight. Finnish ammunition inventory for these guns doesn't seem to have included Pz.Gr 40 APCR-round. But to keep with tank development Finnish Army bought 5,000 Stielgrenade 41 HEAT-bombs to be used with them. These HEAT-bombs arrived in August - November of 1942, were used first for training and later saw also large-scale combat-use. Year 1944 Finnish Army HQ even at one point decided to give every division at least one antitank-gun company armed with 37-mm German at-guns and Stielgrenade 41. The Finns kept using these German 37-mm at-guns until end of World War 2. According wartime plans more modern 75-mm antitank-guns would have slowly replaced them in frontline antitank-use, but the new heavy antitank-guns were not available in numbers large enough to totally replace them before end of the war. Once Continuation War ended in September of 1944, so did the career of these guns in antitank use. About 140 of these guns survived World War 2 and remained warehoused until late 1970's. During that time they saw some training use as infantry guns. Around 1982 - 1984 most of them were sold and exported.

    Losses of 37 PstK/40 antitank-guns during period 9th of June - 7th of July 1944:

    Unit:

    Losses:

    III Army Corps

    5

    V Army Corps

    22

    Total:

    27

    PICTURE: German made 37 PstK/40 antitank gun. (Photo taken in Panssarimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (49 KB).

    Stielgranade 41:

    As other antitank-guns designed before World War 2 during the war also this became outdated due to ever increasing armour protection of new tank designs. German military had huge number of these guns, so they decided to try keeping them at least somewhat up-to-date by developing new ammunition. One of these development was rifle grenade like Stielgenade 41 HEAT-bomb. The Germans manufactured about 636,000 Stielgrenade 41 HEAT-bombs for 37-mm guns in 1942 - 1943. Compared to German wartime total ammunition production for these antitank-guns (over 11.2 million rounds) the number was fairly small. But, it was the ammunition model that still allowed these guns to have some change to fight against new medium and heavy tanks, even if it can be very much considered as an emergency weapon. Basically Stielgrenade 41 was like a very large rifle grenade equipped with high explosive anti-tank (HEAT) warhead. It was fired from end of gun barrel with blank cartridge and could be used both in German 37-mm AT-guns and AA-guns. HEAT warhead was capable of penetrating 180-mm of armour (90-degree angle of impact), making it dangerous to any tank. However, as this HEAT-bomb weight some 8.5 kg and had muzzle velocity of only 110 meters/second, it could be used only from fairly short distance. Maximum range for it was about 600 meters and the effective range only about 300 meters or so.

    Already from 250 meter distance the average dispersion was considerable:

  • Vertical dispersion: 71 cm
  • Horizontal dispersion: 67 cm
  • When flight time of this projectile from that distance (250 meters) was 2.4 seconds, hitting a fast moving tank was not exactly easy. Using Stielgrenade 41 demanded one of the crew to go in front of the gun and push the grenade to end of barrel for each shot, so firing rate wasn't exceedingly high either. To make things even worse Finnish experiences suggest that the ammunition had problems related to quality control. Finnish Army acquired 5,000 rounds of Stielgrenade 41, which arrived to Finland with S/S Ariel in 26th of August 1942. Finnish Army tested the ammunition soon after its arrival by test-firing 22 rounds - with 5 rounds propellant burned only partially resulting HEAT-bomb to fly only few meters before hitting the ground and one round blowing up rupturing the gun barrel. Even if this gun-barrel rupture with Stielgrenade 41 may have been one of a kind with Finnish Army, shooting this ammunition during training was forbidden in Finland and this ammunition type was reserved only for combat use. Reason for the partial burning of propellant proved to be that in blank cartridges used to fire Stielgrenade 41, the grease used to seal the primer of had leaked into detonator and degraded it. When Finnish Army inspected the blank rounds that had arrived with Stielgrenade 41 this quality control issue was discovered in over 1,500 blank rounds and lid used to seal off head of the blank round was not properly tightened in over 1,000 rounds. Hence less than half of the delivered ammunition was actually in working order as delivered.


    SOURCES:

    Werner Haupt: Panzerabwehrgeschütze 3,7 cm - 5,0 cm - 7,5 cm - 8,8 cm-Pak 1934 - 1945 ohne Selbstfahrlafetten.

    Alex Buchner: Deutsche and alliierte heereswaffen 1939 - 1945.

    Erkki Käkelä: Marskin Panssarintuhoojat.

    Risto Erjola: Aseiden valmistus Suomessa vuosina 1939 - 1945

    Article of Markku Palokangas: Anti-tank guns used by Finnish Army (Journal of Military History 17).

    Article of Markku Palokangas: Sotiemme aseveteraanien myöhemmät vaiheet (Ase-lehti magazine vol. 2/95).

    Article of Markku Palokangas: 1944 aseiden vuosi Suomen historiassa (Ase-lehti magazine vol. 6/94).

    Article of Risto Erjola: Ampumatarvikkeet sotien 1939 - 1945 aikana Suomessa (Tiede ja Ase, Suomen sotahistoriallisen vuosiseuran julkaisu N:o 48, 1990).

    Article of Esa Paanen: Suomessa käytetyt panssarintorjunta-aseiden patruunat (Ase-lehti magazine vol. 6/2003).

    Pekka Kantakoski: Punaiset panssarit.

    Jyri Paulaharju: Itsenäisen Suomen kenttätykit 1918 - 1995.

    Article of Lauri Harvila: Panssarintorjunta-aseet (Kansa taisteli magazine vol. 10/1976).

    Terry Gander and Peter Chamberlain: Small arms, artillery and special weapons of the third reich.

    Guns vs Armour by D.M. Honner

    Chris Chant: Artillery of World War II.

    Ian Hogg: Twentieth-Century Artillery.

    Battles of Winter War website Special thanks to its webmaster Sami Korhonen.

    Military manual: 37 mm panssarintorjuntakanuuna vuodelta 1936 (printed 1939).

    Military manual: 37 mm:n pst. kanuunaopas, Saksal. mallit M/37 ja m/40 (printed 1941).

    Military manual: Ampumatarvikenimikkeistö by Puolustusvoimien Pääesikunta Taisteluvälineosasto (printed 1941).

    Military manual: Lyhennetty tykistön ampumatarvikenomenklatuuri (printed 1939).

    Military manual: Jalkaväen Ampumatarvikkeet I by Puolustusvoimien Pääesikunta Taisteluvälineosasto (printed 1941, updated until September 1944).

    Finnish military archives, archive reference T19011

    Finnish military archives, archive reference T19043

    Finnish military archives, archive references T20206/F9, /F10 and /F11

    Special thanks to Sotamuseo (Finnish Military Museum), Helsinki.

    Special thanks to Panssarimuseo (Finnish Armour Museum), Parola.

    Special thanks to Jalkaväkimuseo (Finnish Infantry Museum), Mikkeli.

    Special thanks to Bunkkerimuseo (Bunker Museum), Virolahti.


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