PIBWL Polish Armour page
Main page - Polish armour / armament of armoured vehicles vol.2   - Polish artillery - Steel Panthers - what's new - Links
  © Michal Derela, 2003-2020 Updated: 25. 03. 2020

Armament of the Polish armoured vehicles 1918-39

Part II: Cannons


Part I
 
Part II
 
Machine guns Tank cannons
- 7.92mm wz. 08 (Maxim)
- 8mm wz. 14 (Hotchkiss)
- 7.92mm wz. 25 (Hotchkiss)
- 7.92mm wz. 30

- other machine guns
- machine guns' data
- ammunition 7.92x57mm
- 20mm wz. 38 FK-A
- 37mm wz. 18 (SA-18) Puteaux
- 37mm wz. 36, wz. 37 Bofors
- 47mm Vickers QF
- 47mm wz. 25 Pocisk

Part III:
Artillery of armoured trains

Tank cannons

20 mm Solothurn S18-100

The first trial of using 20 mm gun in a Polish armoured vehicle was made in 1935, when four semi-automatic cannons (anti-tank rifles) Solothurn S18-100 were bought in Switzerland. One of them was mounted and tested in the TKS tankette, what proved, that arming tankettes with 20 mm automatic guns was advisable (more on tankettes with cannons page).

Solothurn gun mounted in a tankette TKS (it can be distinguished from FK-A gun by a shorter barrel and smaller mounting cover).


20 mm wz. 38 model A (FK-A)

This weapon was classified in Poland before the war as the heaviest machine gun (najcięższy karabin maszynowy - nkm). It was designed in 1937 in Fabryka Karabinów (Rifle Factory) in Warsaw by Bolesław Jurek, as "model A" (the designations: FK-A or FK wz.38 are an abbreviation of the factory). An initiator of works upon Polish 20 mm automatic cannon was the airforce, then it was decided, that the weapon must also fulfil demands of the armoured weapons and the infantry, as an anti-aircraft weapon.

Click to enlarge
The prototype of model A gun on anti-aircraft tripod mounting.
Click to enlarge
Pattern tankette TK modified and rearmed with 20 mm FK-A gun

The prototype of model A gun was completed in November 1937. As a tank gun, it was evaluated as better, than tested foreign guns Oerlikon and Madsen. Tests proved, that it was accurate and reliable, its construction was simple and its armour penetration was better, than of tested foreign guns. It penetrated the same armour plates from a distance 200 m further. In 1938, model A cannon was accepted in a limited number as a tank armament and anti-aircraft weapon, until the works upon improved guns (models C and D) would be completed. For anti-aircraft duties, heavy and light tripod mountings were developed.

In May 1939, it was decided to rearm 80 tankettes TKS and 70 tankettes TK with 20 mm guns. Rearming of all tankettes was also considered. Rearming of TKS tankette demanded only minor changes in its armour, but rearming of TK tankette demanded a modification of a superstructure front, making its look similar to TKS. A light tank prototype 4TP (PZInz. 140) and an amphibious tank prototype PZInz. 130 also were to be armed with the 20mm gun, but they did not enter production.

Initially, 200 guns were ordered, to be delivered by February 1940. A serial production started in Zieleniewski factory in Sanok, while barrels were produced in SMPzA factory in Pruszkow. In 1939, hasty efforts were carried out to ensure and coordinate the quickest deliveries of guns, sights, mountings and additional armour parts. The first 10 guns were made in May 1939, the next in July. Until the war, about 50 guns were completed. Most probably only 20–24 were fitted in the first series of rearmed tankettes TKS (possibly even a few less). In the end of 1938, one gun was mounted in a modified TK tankette, as a pattern vehicle. Further fate of this vehicle is not known. Until 25 August 1939 it was planned to rearm 16 tankettes TK, but there is no evidence that any were completed before the war (more on tankettes with cannons page).

The 20mm cannon model A was recoil-operated (short recoil). It could fire single or series shots. It was fed from 5-round box magazines (10-round magazines were in development). As a tank gun, it was fitted with a butt and a telescopic sight.

The ammunition was also developed in Poland, modeled after "long" Solothurn ammunition 20x138 mm (during trial period, Solothurn bullets were used with Polish cartridges). A report from the nkm model A trials says however, that case length was 140 mm (it should be noted, that there is one report, that once in combat the captured German ammunition 2cm Kwk-38 was used, which was also identical as Solothurn, but it raises doubts). The following armour piercing rounds were developed:
- PWS - explosive round with a tracer and base fuze (APHE-T),
- PZS - ignition round with a tracer (API-T),
and practice rounds: PC and PCS (the latter with a tracer).
 For AA duties there were developed: an explosive round LWS with a tracer and a sensitive fuze, practice rounds: LC and LCS (the last with a tracer), and drum magazines 15- and 100-round.
Before the war, about 90,000 AP rounds were ordered.

Gun weight - 57.6 kg, barrel weight without muzzle brake - 20.2 kg, muzzle brake weight - 1 kg.
Gun length with muzzle brake - 2015 mm (without muzzle brake - 1895 mm), barrel length with muzzle brake - 1470 mm (without muzzle brake - 1350 mm), gun width with lock handles - 202,5 mm (without lock handles - 102,5 mm).
Max. range - about 7000 m. Max. bullet velocity - 820 - 858 m/s (depending on ammunition), theoretical rate of fire - 320 rds/min.

Armour penetration:thickness / distance
Carbonated armour plates, perpendicular:20mm @ 300m,15mm @ 500m
Carbonated armour plates, inclined at 30°: 20mm @ 100m,15mm @ 400m
Homogeneous armour plates, perpendicular: 40mm @ 200m,25mm @ 800m,15mm @ 1500m.
Homogeneous armour plates, inclined at 30°:25mm @ 300m,20mm @ 500m,15mm @ 600m.


37 mm wz. 18 (SA-18) / wz. SA Puteaux

Puteaux SA gun for armoured cars
37 mm SA gun for armoured cars in Cardan rectangular mounting.
Puteaux SA gun for armoured cars
37 mm SA gun for armoured cars. Triangular plate on a side was a trunnion base. [9]
Puteaux SA 18 tank gun
37 mm SA 18 tank gun with a telescope sight viewed from above (a barrel is in a recoil), and its barrel with a breech viewed from below. [8]
Renault R-35 tank turret
Inside of APX-R turret of Renault R-35 tank. From the left visible are: a telescope sight, a breech of 37 mm SA 18 m.37 gun and 7.5 mm Châtellerault Mle 1931 machine gun with a magazine.

They were French World War I era short-barrel semi-automatic cannons (SA – semi-automatique), developed by Atelier de Construction de Puteaux (APX). In fact, the designation SA 18 is commonly used in publications for two different, albeit similar guns: the tank cannon (SA 18), and the armoured car cannon (sometimes known as SA 17). Original French designation for better known tank gun was: canon de 37 S.A. pour chars légers (37 mm semi-automatic cannon for light tanks); also known as modele 1918 from its commissioning year, hence SA 18. Polish designation was wz. 18 cannon. The other – probably earlier variant, designated in Poland as wz. SA cannon, was the cannon for cavalry armoured cars (French: canon de 37 mm modèle semi-automatique des autos-mitrailleuses de cavalerie). The armoured car cannon was developed from 37 mm Mle 1916 TR infantry cannon, and a main difference was an adaptation of vertical wedge breech instead of Nordenfeld revolving breech. The tank gun further differed in having thicker and slightly shorter barrel of constant diameter, and a recuparator in thick protected cylinder below. Its barrel, recuparator and other parts were housed in a heavy 33 kg body. The car version was lighter, of classic composition, with slightly conical barrel, sliding above a craddle, which was housing unarmoured recuparator cylinder.

Both cannons were simple and reliable weapons, with quite high rate of fire and a flat trajectory. Their purpose was, first of all, to fight infantry and machine gun nests. The Polish manual credited the tank gun with a "big accuracy", but the known data show rather average accuracy (total dispersion at 300 m was 1.76 m, with 50% shots in 0.66 m diameter circle, according to Krzysztof Gaj). Due to low velocity, their armour piercing capabilities were very poor. However, in 1939 these guns were able to fight most of enemy light armoured vehicles in short distance (up to 500 m). They were manned by one crewman, but a maintenance was simple and jams were rare.

In Poland, 37 mm SA guns of both models were initially used in light tanks Renault FT (about 100-120 guns) and six armoured cars Peugeot. Next, these guns became an armament of 30 armoured cars wz. 28, rebuilt later to armoured cars wz. 34, and of 10 armoured cars wz. 29. In FT tanks and wz. 28 cars these guns were mounted in rectagular mountings with Cardan joint. In armoured cars wz. 29 and part of wz. 34 cars they were mounted in round universal mountings. In 1933-35, six twin-turret tanks Vickers E were temporarily armed with these guns in right turrets. It was also tested in TKS tankette.

Finally, guns wz. 18 in a modified variant SA 18 m.37 (modifié 1937), enabling to fire stronger ammunition, were the main armament of 50 light tanks Renault R-35 and 3 Hotchkiss H-39, bought in 1939 in France. They were mounted there in APX-R turrets, co-axial with 7.5 mm Mle 31 Châtellerault MG.

Specifications

Barrel length: 667 mm (L/18) in tank version, or 740 mm (L/20), of which 634 mm was rifled part, in armoured car version[note 1]. It contradicts with L/21 length commonly quoted in publications. A recoil was approximately 240 mm. The barrel had 12 groves with left twist. In armoured car variant, conical flash suppressor could be screwed upon the barrel.

Weight of the gun was 88 kg (tank version) or 46.7 kg (car version). In the tank version, barrel weight was 31 kg, body weight: 33 kg, recuparator weight: 21 kg, telescope sight weight: 3 kg. In the car version, barrel weight was 25 kg.

Maximum rate of fire was 15 rds/min, practical - 10 rds/min. Breech opening, case ejecting and drawing a firing pin were automatic after a shot (semi-automatic operation). A mounting of a gun was flexible, and the gunner aimed it simply using a butt. It was fitted with a telescopic sight with 1.5x magnification (there are no details in official sources, but Polish SA 18 manual mentions about "zoomed view"). Polish armoured car cannon had wz. 29 telescopic sight with indirect optical axis. Maximum range of fire was stated as 2400 m.

Ammunition

The guns fired cartridges 37 x 94 mm R, with 94 mm case length. In 1939 there was used original French ammunition:
- APHE round Mle 1892 (wz. 1892)
- HE shell Mle 1916 (wz. 1916)

R-35 and H-35 tanks with SA 18 m.37 guns also used more modern APCBC Mle 1935 rounds, of which Poland bought 4644.

In interwar period there were also used old cast iron HE grenades wz. 1888M elaborated with smoke powder (mostly for training), canister shots, illuminating rounds and report rounds (used for sending reports).

SA 18 gun in Renault FT turret.
  Round initial
velocity
round weight
(cartridge weight)
explosive (and notes)
HE Mle 1916 (steel) 365 m/s 560 g (760 g)30 g melinite
HE Mle 1888M (cast iron)402 m/s 455 g (665 g)22 or 20 g smoke powder F3[note 2]
Polish manual:495 m/s 527 g (665 g?)11 g smoke powder F3[note 2]
HE Mle 1937 440 m/s 555 g56 g (not used in Poland)
APHE Mle 1892 (steel)388 m/s500 g (712 g) 15 g smoke powder F3
APCBC Mle 1935600 m/s390 g - (for SA 18 m.37 guns only)
cannister Mle 1908 550 g - (19 balls x 24 g)
cannister Mle 1918 705 g - (25 balls x 24 g)
illuminating 194 g18 g (smoke powder)

Note: there are also differing specifications quoted[note 2]. Polish manual mentioned, that slight differences were caused by different ammunition manufacturers. Case weight was 160 g, average propellant charge was 33 g (with small differences depending on cartridge type).

- APHE round Mle 1892: armour penetration 12 mm at a distance of 0 m (according to this page). Less reliable data: 15 mm at 500 m[5]. There are no penetration of AP rounds stated in military manuals.
- APCBC round Mle 1935 (armour piercing capped with ballistic cap): armour penetration - 21 mm at 400 m.

Cross-sections from French manuals of 37 mm SA guns for armoured cars (left) and tanks (right) – drawings in similar scale for comparison. [11/10]
37 mm SA 18 tank gun from Polish manual. On the left side of the gun there is a telescopic sight. [8]

37 mm wz. 36, wz. 37 (Bofors)

It was a licenced copy of the Swedish Bofors gun, manufactured in Poland by SMPzA in Pruszków (Stowarzyszenie Mechaników Polskich z Ameryki). The gun wz. 37 was a tank variant of a towed anti-tank gun wz. 36, a standard Polish anti-tank weapon. With 300 guns bought in Sweden, the Polish Army had 1200 anti-tank guns wz. 36 (a number of Polish-made guns was also exported to Romania, Spain and Great Britain).
  The first series of 50 tank guns wz. 37 was ordered in March 1937, the second of 61 guns in April 1938. Before the war there were made 111 of them. They were mounted in Bofors-designed turrets in 108 single-turret tanks 7TP, and in tank prototypes 9TP and 10TP. It is not known, if any guns of the 3rd batch, ordered in April 1939, were completed. The guns were fitted with telescopic sights wz.37C.A. and periscope sights wz.37C.A., produced by Polish Optical Works (PZO), the periscope sight was modelled after Zeiss sight. The telescopic sight was used when the tank was not moving, while the periscope sight was used when moving. The wz.37 gun was aimed by a crank gear, and fired by a pedal.

A cross-section of 7TP turret, with wz.37 gun [source 7].

Also original AT-guns wz.36 found some use in armoured weapons. Slightly modified guns were mounted in 2 prototype light tank destroyers TKS-D. According to initial project, they could be mounted either in a vehicle, or on an original wheeled carriage, which was towed by the vehicle (the second way was dropped as impractical, and TKS-D towed an ammunition trailer instead). They were also to be an armament of a projected tank destroyer PZInz.160.

On the left: a back-door view of the 7TP's prototype turret interior (serial turrets had no back door). From the left, visible are: periscopic sight, pistol grip of 7.92mm wz.30 TMG, telescopic sight, 37mm wz.37 gun's breech guard and a pipe for case ejecting, and commander's periscope. An interior of serial turrets was similar.
 On the right: dismounted co-axial mounting of wz.37 gun and wz.30 TMG of 7TP tank.
[Photos - source 7] (Click to enlarge)

Guns wz.36 and wz.37 were semi-automatic, with a sliding block (block opening, ejecting case and drawing a firing pin were automatic). Barrel length - 1665 mm = L/45 (1736 mm with a muzzle brake). Practical rate of fire - 10 rds/min (in a tank gun it might be less, due to more difficult conditions in a tank turret).

Ammunition:
- armour piercing (APHE)
- armour piercing with a tracer (AP-T)
- high explosive - fragmentation (HE-Frag)

- AP round:
muzzle velocity - 800 m/s (Swedish data - 870 m/s); bullet weight - 700 g, explosive weight - 15 g, cartridge weight - 1450 g. Inertial base fuze.
- HE-Frag shell:
explosive weight - 48 g, impact fuse, max. range: 7100 m.

As for armour penetration, there can be different data found. Anyway, 37mm Bofors gun could destroy any armoured vehicle in 1939 from a distance below 1km, and its performance made it one of the best 37mm AT guns of that time.

Penetration according to the source [1]:

- vertical armour plate:
60 mm at 300 m, 48 mm at 500 m, 30 mm at 1000 m, 23 mm at 1500 m, 20 mm at 2000 m;
- hit angle 30° (plate inclined at 60° from vertical?):
40 mm at 100 m (this value is also given by source [6]).

Penetration according to the Swedish data and the Finnish manual:

- armour plate inclined at 30° from vertical:
40 mm at 300 m, 33 mm at 500 m, 18 mm at 1000 m.

Other sources give also values: 40 mm at 500 m; 25 mm at 1000 m.

47 mm V.A. wz. E (Vickers QF)

Armata 47 mm Vickers
47 mm Vickers gun in a coaxial mounting with wz. 30 machine gun.

It was British tank gun developed by Vickers-Armstrongs for export only. Primarily, it was an armament of single-turret light tank Vickers E (6-ton) Alternative B (Type B). They weren't used by the British Army in greater numbers. 22 of these guns were bought in 1934 by the Polish Army, with whole turrets, which were next used to convert 22 twin-turret Vickers E Type A to single-turret Type B standard. Polish manual named this gun as "47 mm V.A. wz. E" tank gun, but it seems, that it was rather an extrapolation from the tank's original designation (Vickers-Armstrong Mk. E – though the tank was never known as "wz. E" in Poland).

Barrel length: 986.8 mm (L/21). The ammunition consisted of armour piercing rounds (probably APHE) and high explosive shells (HE). Muzzle velocity was 488 m/s (AP) or 300 m/s (HE). Projectile weight was 1.5 kg for both rounds. Rate of fire was up to 10 rds/min[7].

Armour penetration was 25 mm at 500 m (vertical) or 16 mm at 1200 m inclined at 60°[7]. A telescopic sight was to the left of the gun. Maximum range of AP round was theoretically 5600 m[7], but according to Polish tests, the gun was able to fight armoured vehicles up to 1000 m only, due to big dispersion and poor sights. Range of HE round was 3500 m.

Vickers Mk.E Type B cross-section - the 47mm gun in a turret (based on a drawing by M. Baryatynski).


47 mm wz. 25 Pocisk

This gun was designed in Polish factory Ammunition Works "Pocisk" ("The Bullet") in 1925, for an infantry gun contest. The designer was Austrian Edmund Rögla, working in Poland after World War I. That year, two prototypes were built, and in 1926 Polish Army ordered four guns for comparative trials with foreign guns. It was quite good design - the first modern gun designed in Poland. Its peculiar feature was twin-tail articulated gunbed with pivoting wheels, which could be fixed in upper or lower position to lower its silhouette. The gun did not enter production, however, because in 1930 the Army changed demands and requested better armour penetration, and then decided not to equip the infantry with special small-caliber guns at all. Six to ten guns were manufactured in total. They were not adopted as infantry guns and were stored, but in 1932 four guns were fitted in experimental light self propelled guns TKD (built upon tankette chassis). These vehicles were used in a number of Army manouvres and in regaining of Czech Zaolzie in 1938, but it is not known if they were used in 1939. There was only limited ammunition supply made with the guns.

Pocisk guns were also considered as an armament of Vickers E light tanks, and a new tank variant with 1475 mm barrel (L/31) was developed in 1935 in this purpose, but its anti-tank performance was inadequate. In 1936 there was constructed new 40 mm L/55 gun, but 37 mm Bofors gun was chosen for new tanks eventually, while plans to rearm Vickers tanks were abandoned.

A prototype of 47mm wz.25 "Pocisk" infantry gun - and a light self-propelled gun TKD.

47mm wz.25 gun was semi-automatic, with a pivoting breechblock. Maximum rate of fire was up to 16 rds/min. There is no information on barrel length in publications. The gun was equipped with Goertz panoramical sight. Maximum range was 6000 m. Elevation in TKD was -12 +23°, in a towed variant -13,4+44°.

Ammunition: armour piercing high explosive (APHE), high explosive (HE) and a cannister.

- AP round:
muzzle velocity - 400 m/s, projectile weight - 2.08 kg, explosive weight - 42 g.
Armour penetration was 25 mm at 750 m, but it was tested against low quality plates.
- HE shell:
muzzle velocity - 365 m/s, shell weight - 1.94 kg, explosive weight - 128 g. Max. range 6500 m.
- cannister:
weight - 2.46 kg, 134 balls.



Armoured trains' artillery:

Armoured trains' artillery was moved to a separate page.



Notes:

1. SA 18 barrel length was 667 mm from chamber's cone to muzzle according to technical drawing in French 1918 manual [10]. Also Polish 1932 manual quoted rounded value of 67 cm [8]. These data indicate barrel length L/18 and are contradictory with commonly given L/21 value. In armoured car variant, barrel length was 740 mm (L/20) according to Polish manual [9] - corresponding with values given for Mle 1916 TR infantry gun.

2. Specifications of 37 mm rounds (apart from Mle 1935 and Mle 1937) are given according to Polish SA 18 gun manual [8], but slightly differing stats can be found in other sources as well. For old cast iron Mle 1888M shell we showed in the first place different specifications from French manuals for armoured car cannon, which seem more reliable: initial velocity 402 m/s (Polish manual: 495 m/s) and shell weight 455 g (Polish value 527 g is much too big for 665 g weight quoted for "ordinary cartridge", considering case and propellant weight). There is also different weight of smoke powder in the shell: 22 g in French 1933 manual or 20 g of black powder in 1924 edition, instead of 11 g in Polish one – a bigger value seems more probable to obtain proper effect. According to the same manual, Mle 1916 HE shell's weight was 555 g instead of 560 g (with the same total weight 760 g and explosive weight 30 g). Older 1924 instruction quoted 560 g shell weight, but only 25 g of explosive. It might be noted, that in Polish manual for armoured car cannon from 1938, ammunition specifications are given only in general way, but have been apparently confused. Polish literature and both manuals state, that maximum velocity of rounds fired from these guns was 495 m/s, but this value concerned only old cast iron HE shell, which, according to all French manuals, had velocity 402 m/s. However, it is interesting to note, that Polish manual credits it with as much as 46 g of BC propellant powder, while according to French sources it had only 33.5 g (a value similar to other rounds).


Sources:
1. Janusz Magnuski, Czołg lekki 7TP - część pierwsza, Militaria vol.1 No.5 - special issue
2. Rajmund Szubański, Polska broń pancerna 1939; Warsaw 1989
3. Janusz Magnuski, Pociąg pancerny "Śmiały" w trzech wojnach; Pelta; Warsaw 1996
4. Leszek Komuda, Przeciwpancerne tankietki in: Militaria vol.1 no.4
5. Witold Jeleń, Rajmund Szubański: Samochód pancerny wz.29; TBiU nr 84; Warsaw 1983.
6. A. Konstankiewicz, W. Słupczyński: Armata przeciwpancerna wz.36, TBiU nr 45, Warsaw 1977
7. Michał Kuchciak: Czołg lekki Vickers 6-Ton w Wojsku Polskim w latach 1931-1939, Oświęcim 2018
8. Andrzej Konstankiewicz: Broń strzelecka i sprzęt artyleryjski formacji polskich i wojska Polskiego w latach 1914-1939, Lublin 2003, ISBN 83-227-1944-2
8. Armatka czołgowa 37 mm wz. 18 systemu "Puteaux". Ministerstwo Spraw Wojskowych, Warszawa 1932
9. Regulamin broni pancernej. Armatka samochodowa 37 mm wz. S.A. Opis i utrzymywanie sprzętu, Ministerstwo Spraw Wojskowych, Warszawa 1938
10. Canon de 37 S.A. pour chars légers, Ateliers de construction de Puteaux, 1918
11. Instruction sur le canon de 37 mm modele semi-automatique des autos-mitrailleuses de cavalerie, Ministere de la Guerre, Paris, 1924 & 1933


Update history:
25. 03. 2020 - page modernized, enhaned information on Puteaux, Vickers and Pocisk guns, excluded armoured trains' artillery
19. 07. 2008 - corrected and improved armoured train's artillery, added 2 photos, other minor text improvements



[ Main page ] [ Polish armour ] [ Polish artillery ] [ Steel Panthers ] [ Links ]

You can mail me with any questions or comments. Corrections or photos are welcome.

All photos and pictures remain the property of their owners. They are published in non-commercial educational and research purpose.
Text copyright to Michal Derela.