3.7 cm PaK 36

The Pak 36 (Panzerabwehrkanone 36) was a German anti-tank gun that fired a 3.7 cm calibre shell. It was the main anti-tank weapon of Wehrmacht infantry units until mid-1941. It was followed in this role by the 5 cm Pak 38 gun.

History
Design of a horse-drawn, 3.7 cm anti-tank gun (designated 3.7 cm Pak L/45) by Rheinmetall commenced in 1924 and the first guns were issued in 1928. By the early 1930s, it was apparent that horse-drawn artillery was obsolescent, and the gun was modified for motorized transport by substituting magnesium-alloy wheels and pneumatic tyres for the original spoked wooden wheels. Re-designated the 3.7 cm Pak 35/36, it began to replace the 3.7 Pak L/45 in 1934 and first appeared in combat in 1936 during the Spanish Civil War. It formed the basis for many other nations' anti-tank guns during the first years of World War II. The KwK 36 L/45 was the same gun, but used as the main armament on several tanks, most notably the early models of the Panzer III. Even the Soviets used the PaK 36 carriage design for their 45mm M1937 AT gun.

Operational history
During the May 1940 Western Campaign, the Pak 36, being a small-calibre weapon, was found to be inadequate against allied tanks like the British Mk.II Matilda, and the French Char B1 and Somua S35. Still, the gun was effective against the most common light tanks, such as the R35, during the Battle of France, where the Char Bs and Matildas represented but a small fraction of the total number of AFVs. In June 1941, the Soviet forces consisted of 10,661 T-26, 2,987 T-37/38/40/50s, 59 T-35, 442 T-28, 7,659 BT, 957 T-34, and 530 KV for a combined total of approximately 23,295 tanks. Thus, during the initial phases of Operation Barbarossa, the Pak 36 could still penetrate the armor of the majority of Soviet AFVs at ranges up to 1000m from the front, with the notable exception of the T-28s and T-35s, which it could only penetrate at under 100m. The Pak 36 could not penetrate the armor of the T-34s and KVs.

By late 1941, however, the widespread introduction of Soviet medium tanks quickly erased the gun's effectiveness; miserable performance against the T-34 on the Eastern Front led to the Pak 36 being nicknamed Heeresanklopfgerät (literally "army door-knocking device"), for its inability to produce any effect on the T-34 aside from notifying the tank of its presence by futilely bouncing rounds off its armor (regardless of the angle or distance).

The Pak 36 began to be replaced by the new 5 cm Pak 38 in mid-1940. The addition of tungsten-core shells (Pzgr. 40) added slightly to the armour penetration of the Pak 36. Despite its continued impotence against the T-34, it remained the standard anti-tank weapon for many units until 1942. With tungsten core rounds, the Pak 36 crews could finally achieve kills on T-34s, but only via a direct shot to the rear or side armour from point-blank range, an unlikely and rather suicidal scenario. The advantages of the Pak 36 were its ease of handling and mobility where it could be brought into action very rapidly by as little as two men (it weighed only 432 kg), its good quality optical aiming devices, that it was small and easy to conceal, and that it had a very high rate of fire.

As the Pak 36 was gradually replaced, many were removed from their carriages and added to SdKfz 251 halftracks to be used as light anti-armour support. The guns were also passed off to the forces of Germany's allies fighting on the Eastern Front, such as the 3rd and 4th Romanian Army. This proved particularly disastrous during the Soviet encirclement (Operation Uranus) at the Battle of Stalingrad when the Romanian forces, already demoralized and understrength, bore the brunt of the main Soviet armored thrust, and were unable to stop the Soviet advances due to their grossly inadequate anti-tank weaponry. The Pak 36 also served with the armies of Italy, Finland, Hungary, and Slovakia.

Although the Pak 36 quickly became ineffectual in the European and Russian theatres, in China. the Pak 36 was still viable as an effective anti-tank gun. It could destroy the Japanese Type 95 Ha-Go and Type 97 Chi-Ha tanks, since their armor protection was quite weak. For example, during the Battle of Taierzhuang, the Chinese PaK 36 destroyed a number of Japanese tanks

37mm Pak 36 L/45 ammunition

 * Pzgr
 * Projectile weight: 0.685 kg
 * Muzzle velocity: 745 m/s

This was tungsten cored ammunition, lighter and with a higher muzzle velocity, produced in small quantities.
 * Pzgr 40


 * Projectile weight: 0.368 kg
 * Muzzle velocity: 1,020 m/s

Penetration figures given for Pzgr 40 and an armoured plate 30 degrees from the horizontal.

Stielgranate 41
In 1943, the introduction of the Stielgranate 41 shaped charge meant that the Pak 36 could now penetrate any armour, although the low velocity of the projectile limited its range. The Pak 36s, together with the new shaped charges, were issued to Fallschirmjäger units and other light troops. The gun's low weight meant that it could be easily moved by hand, and this mobility made it ideal for their purpose.

Variants

 * 40 mm 40M – This was a Hungarian design. It was effectively a Pak 36 but rebarrelled to fit a Škoda 40 mm A17, the standard Hungarian light anti-tank gun. This could fire the same ammunition as the Bofors 40 mm anti-aircraft gun, and also had a version of Stielgranate ammunition made for it.
 * 37 mm anti-tank gun M1930 (1-K) – This was a Soviet anti-tank gun designed by Rheinmetall, which was very similar to the Pak 35/36, but lacking some improvements.