PICTURE: 37 PsvK/18 (37-mm SA-18 Puteaux) tank gun on turret of Renault FT 17 tank. (Photo taken in Panssarimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (146 KB).

This was French 37-mm SA-18 Puteaux tank-gun. Finnish Army used these tank guns in Renault FT 17 tanks. Year 1919 Finnish Army bought 32 tanks from France, 14 of these 32 tanks were equipped with these 37-mm guns. The next year France delivered two more Renault FT 17 tanks, one of these two tanks was armed with this gun, bringing the total number of these tank guns in Finnish use to 15 guns. They were also temporily used to equip some Vickers 6-ton tanks for war games for summer 1939, but in that case the gun mounting was so weak, that it allowed only shooting blanks. Considering it was one of the first tank guns ever 37 Psv.K/18 (as Finnish Army called this gun) was surprinsingly reliable and accurate, but for practical reasons (one soldier doing both reloading and shooting) the practical rate of fire was not very high (about 10 shots/minute at most). It had been equipped with simple but useful optical sight with 1X magnification (in other words: no magnification) and fired the same 37 mm x 94 R gun shells as 37-mm Russian Obuhov and Rosenberg infantry guns and 37/30 Ma (37-mm Maxim) automatic cannon. Needless to say the optical sight was a straight-through telescopic sight, that moved with the gun when elevation was changed - often resulting the gunner needing to shoot while in ankward position. As usual with tank guns, the gun was semiautomatic of sort - after firing a shot it automatically removed cartridge case and breech remained opened for loading of the next shell. At least partly due to this the gun had rather versatile ammunition inventory in Finnish use, but due to its low muzzle velocity (caused small cartridge case, small propellant charge and short L/21 gun barrel), the gun was ineffective both against armoured vehicles and other structurally strong targets like bunkers.

PICTURE: 37 Psv.K/36 tank gun in Vickers 6-ton tank. (Photo taken in Panssarimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (88 KB).

This was the tank-gun version of 37 PstK/36 (37 mm antitank-gun M/36) antitank-gun designed by Bofors in Sweden. Like the antitank-gun it was designed by Bofors. The tank gun was known as 37 Psv.K/36 (37-mm tank cannon model 1936) and was a Finnish choice as main gun for Vickers 6-ton tanks ordered from Vickers Armstong Ltd in year 1936. As with antitank-gun version it was to be manufactured locally, since manufacturing licenses of Bofors designs were obtained from Bofors to VTT (Valtion Tykkitehdas = State Artillery Factory) for this purpose in year 1937. Finland had ordered its 6-ton tanks from Vickers Armstrong without weapons, as according the plan VTT was to manufacture their main guns, while coaxial machinegun and hull submachinegun would also be Finnish-made. February of 1939 order of 33 guns was made to VTT, but first Vickers 6-ton tanks were not equipped with them until December of 1939 and most of the tanks did not receive their guns by end of Winter War. Quite similar tank guns were also used by Polish and Swedish military in their light tanks and in some armoured cars. In addition Landsverk armoured cars delivered to Netherlands before World War 2 had been equipped with similar tank guns. After Winter War (1939 - 1940) Finnish Vickers 6-ton tanks were equipped with captured Soviet 45-mm tank guns and the resulting tank was renamed as T-26E. However this short-lived use in Finnish tanks didn't completely end the use of these tank guns in Finland. After Winter War Finland started building new fortified defence line known as Salpa-line near new eastern border. Some of the bunkers on that line were equipped with modified tank turrets originating from captured BT-2 tanks and were equipped with remaining 37 Psv.K/36 tank guns.

As usual with tank guns, the gun was semiautomatic of sort - after firing a shot it automatically removed cartridge case and breech remained opened for loading of the next shell. It had useful high explosive shell and armour piercing capability comparable to other tank gun designs of the similar caliber introduced in 1930's. This meant that while it in year 1939 it perfectly capable penetrating frontal arch armour of most tanks from reasonable distance, it became ineffective against the new more heavily armoured tank designs introduced during the war.

When these tank guns were ordered the original plan was to equip them with German Zeiss TZF gun sights, but since Germany refused to deliver these due to Molotov-Ribbentrop pact banning Germany from supplying military equipment to enemies of Soviet Union, Finnish military had to find a replacement. The gun sight acquired for them at that time was (presumably British-made) very simple optical sight with only simple crosshair reticle. As to be expected the optical sight was straight-through telescopic sight type. The same sight was used also for coaxial 7.62-mm M/09-31 (tank) machinegun. Needless to say making range-estimation with this sort of gun sight proved difficult. When the gun could be aimed laterally only by rotating the turret and the dials used for aiming it didn't have any markings, like elevation settings, this must have further complicated hitting the target. These factors likely benefitted to rather poor combat performance of Finnish Vickers 6-ton tanks during Winter War.

PICTURE: Captured Soviet 45-mm tank gun in Finnish T-26E tank. (Photo taken in Panssarimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (124 KB).

- "Guns vs Armour website" by D.M. Honner (B-250 and BR-240 APHE, 760 m/sec):

distance	hitting angle	penetration
100 m	90 degrees	52 mm
500 m	90 degrees	43 mm
1000 m	90 degrees	35 mm
1500 m	90 degrees	28 mm
2000 m	90 degrees	23 mm
100 m	60 degrees	43 mm
500 m	60 degrees	35 mm
1000 m	60 degrees	28 mm
1500 m	60 degrees	23 mm
2000 m	60 degrees	19 mm

distance	hitting angle	penetration
500 m	90 degrees	47 mm

distance	hitting angle	penetration
500 m	90 degrees	53 mm
1000 m	90 degrees	40 mm
1500 m	90 degrees	30 mm
500 m	60 degrees	44 mm
1000 m	60 degrees	33 mm
1500 m	60 degrees	25 mm
500 m	30 degrees	16 mm
1000 m	30 degrees	12 mm
1500 m	30 degrees	9 mm

distance	hitting angle	penetration
100 m	70 degrees	57 mm
200 m	70 degrees	55 mm
300 m	70 degrees	53 mm
400 m	70 degrees	52 mm
500 m	70 degrees	50 mm
600 m	70 degrees	48 mm
800 m	70 degrees	45 mm
1000 m	70 degrees	42 mm
1500 m	70 degrees	35 mm
2000 m	70 degrees	28 mm
2500 m	70 degrees	22 mm

Year 1932 the Soviets introduced not only 45-mm antitank-gun, but also 45-mm tank gun, which was known in factory designation 20K. In 1930's this gun became the standard Soviet tank gun used in large variety of tanks and armoured cars. It remained continuously in production until year 1943 and by the time production ended about 29,700 guns had been made. As with 45-mm antitank-guns also these tank guns were further developed during their manufacturing. Also as with 45-mm antitank-guns the first version (M/1932) lacked effective semi-automatic breech mechanism (capable removing the used cartridge case after firing a shot and breech remaining open for the next round). This semi-automatic loading process was based to inertia, which heavier but notably slower high explosive shells failed to provide in Pst.K/32 version. Hence its breech mechanism worked as intended way with rounds that had antitank shells, but not with rounds equipped with high explosive shells. The improved breech mechanism with improving allowing this was introduced with 45-mm tank guns (45 Psv.K/34) in year 1935 and made a notable difference in maximum rate of fire possible. These tank guns had similar barrel length (L/45) as 45-mm antitank-guns and used same ammunition - therefore they had also indentical ballistics and armour penetration capability.

During Winter War (1939 - 1940) and Continuation War (1941 - 1944) Finnish Army captured large number of Soviet armoured vehicles equipped with these guns. Finnish Army reissued over hundred Soviet tanks and over two dozen heavy armoured cars equipped with them. Shortly said during World War 2 captured 45-mm Soviet tank guns were the most numerous tank guns in Finnish use. Soviet manufactured tanks in Finnish use equipped with these guns included BT-5, BT-7, T-50 and variety of T-26 tanks. The Soviet-manufactured armoured cars in Finnish use and equipped with the same guns included BA-3, BA-6 and BA-10 armoured cars. In addition to all these Soviet-manufactured vehicles after Winter War the Finns equipped all their remaining (25) Vickers 6-ton tanks with these guns and coaxial DT-machineguns - the resulting tank was named as T-26E. With these armoured vehicles captured 45-mm Soviet tank guns served Finnish Army until year 1960. Soviet 45-mm tank guns used the same 45 mm x 310 R ammunition as antitank-guns and had similar ballistics.

Finnish Army divided 45-mm tank guns as three separate models:

Besides being used with armoured vehicles, year 1944 Finnish Army used 45-mm tank guns also in Salpa-line. That year several dozen turrets originating from captured Soviet armoured vehicles were added to bunkers of the particular defence line. In this use the turrets retained their original armament - 45-mm tank gun and 7.62-mm coaxial DT-machinegun. After Winter War the Finns developed also a 45-mm bunker gun, which was based to captured Soviet tank guns of the similar caliber, but was quite different from technical aspect.

The gun-sight that Finnish Army used with captured 45-mm tank guns was their original Soviet m/30 (Tol) gun-sight. It was the usual straight-through telescopic sight and in addition of 45-mm was also used for coaxial 7.62-mm DT-machinegun. The reticle has their sets of markings for armour piercing shells, high explosive shells and coaxial machinegun, which provided the correct reference points for shooting to various ranges. The reticle has these reference points for armour piercing shells for every 100 meters, for high explosive shells for every 50 meters and for coaxial machinegun to distances of 400, 600, 800 and 1000 meters.

German tank gun, which Finnish Army used in Stu 40G assault guns and Pzkw IVJ tanks. Finland bought 59 Stu 40G assault guns from Germany 1943 - 1944 and 15 Pzkw IVJ tanks in year 1944. More to come...

Soviet tank gun, which Finnish Army used in captured T-28 tanks. Two T-28 were captured in Winter War and during first year of Continuation War (1941) several more were captured. From those T-28 tanks captured in year 1941 five tanks were taken to Finnish use bringing the total number in Finnish use to seven tanks. More to come...

Soviet tank gun, which Finnish Army used with captured T-34/76 tanks. Four of these captured tanks were taken to Finnish use during Continuation War and three more bought from Germany in year 1944. Repairs of two additional T-34/76 were completed only after ending of the war bringing the total number of T-34/76 tanks in Finnish use to nine tanks. More to come...

Soviet tank gun, which Finnish Army used with captured KV-1E m 1941 heavy tank. Only one of these captured tanks saw Finnish use. More to come...

Soviet tank gun, which Finnish Army used with captured KV-1 m 1942 heavy tank. Only one of these captured tanks saw Finnish use. More to come...

British World War 1 era (114 H/18 howitzer, which VTT (Valtion tykkitehdas = State Artillery Factory) adapted for new Finnish build BT-42 assault gun (techically: self propelled artillery piece). Essensially the assault gun a new State Artillery Factory designed and build build turret on hull of captured Soviet BT-7 tank. 18 of these unsuccessful assault guns were build during Continuation War. More to come...

Soviet 152 H/37 howitzer was used as main gun of ISU-152 heavy assault gun. Summer of 1944 Finnish Army captured two of these assault guns. One of the two captured assault guns needed extensive repairs, but the another one saw brief Finnish use before being lost in battle. More to come...

SOURCES:

Alex Buchner: Deutsche and alliierte heereswaffen 1939 - 1945.

Erkki Käkelä: Marskin Panssarintuhoojat.

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

Pekka Kantakoski: Punaiset panssarit.

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

Chris Chant: Artillery of World War II.

Ian Hogg: Twentieth-Century Artillery.

Military manual: 45 mm Jv. tykkiopas by Päämaja. (Printed 1940)

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

Military manual: Kenttätykistön ampumatarvikkeet by Puolustusvoimien Pääesikunta Taisteluvälineosasto (printed 1940, updates added until 1947).

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

Finnish Military Archives folder T19052/2

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

Guns vs Armour by D.M. Honner

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

Documents from folder T/20207 /F16 sal in Sota-Arkisto (Finnish Military Archives).

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