Pak 36 Anti Tank Gun

Many weapons acquire nicknames given by the soldiers who use them. Mostly these are humorous familiarities, but in some cases, the term can be derogatory, such as the German army’s 3.7cm Pak 36 anti-tank gun, referred to as the ‘Door Knocker’. To be fair, it was not always known as that and in the early days of its service life in the mid-1930s, the gun was considered to be a very modern and effective weapon. Its combat effectiveness as an anti-tank gun was demonstrated to the world during the Spanish Civil War between 1936 and 1939 and in the early months of WWII, it remained a dominant weapon.

A closer look

In the 1920s, designers of anti-tank (AT) weapons were trying to keep ahead of tank development and investigated different calibres in defeating armour protection. Even in Germany, which had been denied specialist AT artillery by the terms of the Versailles Treaty of 1919, companies such as Rheinmetall began the development of a project known as 3.7cm calibre weapon Pak L/45. The term, Pak stood for ‘Panzerabwehrkanone’ and the L/45 was the length of the barrel in terms of calibre. Mounted on a wheeled horse-drawn carriage, it was available by 1928. Into the 1930s and re-armament of the German army, the gun was shown to be outdated for the emerging new tactics.

The gun design itself was serviceable but it needed to be modernised. This meant fitting pneumatic tyres and configuring it to be towed by motorised vehicles. The result was the creation of the Pak 35/36, fitted with a distinctive gun shield, which was first demonstrated in 1934 and entered service in 1936. The calibre remained the same, as did the barrel length and versions of it would be fitted to the first tanks of the German army as the KwK36 L/45.

After witnessing its effectiveness during the Spanish Civil War, the reports filed by Russian observers led to the development of a copy known as the 45mm calibre M1937 AT gun.

Russia also acquired the rights to produce the weapon under licence in the 37mm calibre, examples of which were in service when the country was attacked in June 1941. Any versions of these captured by the Germans were designated Pak 158(r) and used against their former owner.

When Poland was attacked in September 1939, German units deployed with the Pak 35/36 where it had little trouble in defeating the light tanks of the Polish army. At that time, the German army had over 9,000 of the guns in service, which would remain in service throughout the war and continued in production, with a further 5,339 being issued to the army. In addition, a further 6,000 weapons were produced for supply to overseas sales. Some had been sold to Holland before the war, which were later captured in 1940. The irony was the Germans re-used these versions, giving them the designation of 3.7cm Pak 153(h), which identified them as having been captured from Holland.

Lack of punch?

The Pak 36 had no problem in defeating the armoured vehicles in the Dutch and Belgian armies but later in the campaign of 1940, the gun proved inadequate against heavier French and British tanks. It was during these engagements that the crews began to call the weapon either the ‘Heeresanklopfgerat’, which literally translates to mean the ‘army door-knocking device’ or the ‘PanzerAnklopfKanone’ (still Pak) to mean ‘tank door-knocking canon’. There was nothing wrong with the gun itself, the problem lay in the ammunition, which was too light and lacked muzzle velocity. The projectile was a solid steel shot, with a small explosive charge weighing only 1.5 lbs. The muzzle velocity was less than 2,500 FPS.

Served by a crew of five, two in an emergency, it weighed around 723 lbs in action, achieving a rate of fire of up to 13 rounds per minute, due to the ‘fixed’ type of ammunition. However, in action, this was rarely needed. The gun could fire three main types of this standard ammunition, which included the Panzergranate, the tungsten-cored Panzergranate 40 (Armour-piercing Core Rigid) and the 1.33 lbs high explosive round. The projectile of the Panzergranate 40 weighed only 12.5oz but its muzzle velocity was increased to over 3,300 FPS and could penetrate 64mm of armour at 100 yards, which dropped to around 40mm at 500 yards. The maximum range to which the projectile carried was 4,400 yards, but the effectiveness dropped off markedly at ranges over 300 yards.

New projectile

In 1941, the Pak 36 was shown to perform very poorly against the T-34 and by 1942, it was an outclassed weapon. However, it remained in service and was fitted to vehicles such as the SdKfz 251 half-track to provide fire support to the infantry. Fallschirmjager (parachute) units liked the gun because of its compact design and light weight, which allowed it to be manoeuvred quickly. Then, in 1943 the gun was given a new lease of life with the introduction of a new type of ammunition called the Stielgranate 41.

This new projectile resembled a very large mortar bomb and its shape meant it had to be fired from outside the barrel. Weighing 19 lbs and fitted with a bulbous shaped warhead and stabilising fins, the round was slid over the outside of the barrel. A special blank cartridge was loaded as normal and on firing, the propelling gases would launch the Stielgranate out to ranges of more than 800 yards. The shaped charge warhead with a diameter of 6.3” contained 5.3 lbs of TNT and could penetrate armour up to 180mm using the chemical reaction of the explosive charge. The projectile measured 29” in length and was fitted with a fuse in the warhead for direct hits and another in the tail section which would detonate if the target was only ‘grazed’. It had a low muzzle velocity of only 360 FPS, which affected its accuracy when engaging targets beyond the range of 300 yards.

The Pak 36 was copied by the Japanese to produce an AT gun called the Type 97 and Germany’s ally, Hungary produced a version with a 40mm calibre. Even America was influenced by its design, which led to the M3A1 37mm AT gun. Most of Germany’s allies used the Pak 36 and Italy even produced a version under licence, known as the Cannone contracarro da 37/45. When Italy capitulated in 1943, the Germans seized these and they were designated as the Pak 162(i). As the war progressed, the Pak 36 was outclassed by more powerful AT guns developed to meet the threat of heavier tanks. It continued to be used throughout the Russian campaign and some were still in use until just before the end of the war.

Re-enactment

Such a service history means this small gun has a massive interest factor to re-enactors, weapon enthusiasts, modellers and collectors. Scale models of the weapon come in all sizes and materials, from small plastic kits to large metal kits, with excellent detail to fit into great scenarios. Collectors can indulge their interest by purchasing examples of inert ammunition, including Stielgranate 41 rounds which occasionally come up for sale, ammunition boxes, sight units and training manuals. Ownership of an original Pak 36, like other large items, is possible but be prepared to find somewhere to keep it. There are specialist websites offering the guns for sale, including private owners wishing the sell.

Replicas can be found for sale online, which re-enactment groups may consider, such as www.military-muckabouts.webs. com, which produces weapons that have been used in films. Alternatively, there is always the option of hiring an example of a Pak 36 for an event, if ownership does not appeal to a group. This service is offered by www. gunhire.co.uk and removes the worry of storage. Static displays by re-enactment groups depicting German units often include either a real or replica example of the Pak 36 and a selection of types of ammunition. Some groups also use their Pak 36 in battle re-enactment scenarios, where the manoeuvrability of the weapon, which made it popular with Fallschrmjager units, can be demonstrated. Watching such displays is so much more rewarding than seeing them static in a museum, but if that is all that is available, then it is still worth making the most of the opportunity to see a piece of history in detail.