Backbone of the German Anti-Tank Corps
The Wehrmacht was always trying to stay ahead of the arms race that had developed in the 1930s. Whilst the 3.7cm Pak 36 anti-tank gun had acquitted itself very well during the Spanish Civil War, it was thought that an upgraded version was needed in order to stay ahead of the gun-armor spiral. Rheinmetall-Borsig AG was asked to improve upon their original design. What they came up with was the 5cm Pak 38 with a L/60 barrel (a barrel 60 calibers in length), which met approval for production in 1939. However, soon after the factories geared up for production, the German military became aware of newer tank designs by the Soviets (thanks in part to the Molotov-Ribbentrop pact) and therefore ordered an upgunning of the Pak 38.
Originally, Rheinmetall wanted to just change the barrel of the previous Pak 38 but, because the Luftwaffe was given priority for lightweight alloys, the design also needed to be changed. As a result, a new carriage was developed using all steel construction.The gun’s traditional split trail was supported by torsion springs and, like the Pak 38, a third wheel could be attached to the trail spades for easier manhandling. For ease of production and economic use of resources, the curved gun shield of the Pak 38 was dropped and replaced with a more angular twin plate shield.
The gun was equipped with a L/46 barrel with a larger double-baffled muzzle brake. The gun mechanism was of the ‘horizontal sliding breech block semi-automatic variety’” which allowed for a more rapid rate of fire, as the previous shell was expanded and the breach was left open for the next shot. Because of the weight and size, the gun was seen as a motorized piece and was equipped with solid rubber tires which allowed it to take the harsh punishment of the frontlines. If the need arose, it could be used in an indirect fire role.
Photos: Wikimedia Commons
The above pictures are of a horizontal sliding semi-automatic breech block. The operating handle is pulled to the opening position, this pushed the block to the side (to the right in the case of the PaK 40) and then a shell is pushed into the breach. The operating handle is then pushed to close the breach and make the gun ready to fire. The layer of the gun would then press the trigger on his elevating handwheel triggering the gun. The recoil would then reopen and eject the spent shell casing and recock the mechanism. This then allows for a new shell to be pushed into the breach, which would then close automatically without the need to touch the operating handle.
The sights were the standard ZF 3 x 8 (3 x magnification, 8-degree field of view) that equipped Anti-Tank (AT) guns of the German military, but it was an improvement over the earlier ZF 3 x 8’s (as used on Pak 38’s) in that it had an upgraded reticule which allowed for better leading of targets, and better degrees of accuracy.
Overall, the cost was 12,000 Reichmarks (RM) per unit (approximately $48,940 in 2017), which was a significant leap over the 8,000 RM (approximately $32,625 in 2017) of the Pak 38. It also required 2200 man hours and 6 months production time per unit.
On the Frontlines
Originally, the Pak 36 and 38 were performing adequately enough that the Pak 40 project was not seen as a necessity. However, once Operation Barbarossa (the invasion of the Soviet Union) began and the German military encountered the heavily armored KV-1 and steeply angular T-34, the Pak 38 struggled to penetrate except at point blank ranges. The Pak 40 was speedily pushed into high gear and the first pre-production models were ready in November 1941. These initial models proved their worth on the Eastern Front and approval was given for production. By the end of 1942, over 1,300 Pak 40s were on the frontlines. It was decided in 1943 to make it the standard AT gun in German service. It was so successful that by the end of the war about 23,000 had been produced and supplied to over 9 countries.
PaK 40 and crew in training in France, 1943. Photo: Bundesarchiv
The vast majority of PaK 40’s (about 20,000) served within the German military. It saw action first on the Eastern Front, where its high-velocity armor-piercing shells easily penetrated most Soviet armor encountered. By the beginning of 1943, the PaK 40 had become the core of the Wehrmacht anti-tank arm. It saw service on all fronts that Germany was fighting, from North Africa and Italy, from France to the Eastern Front.
Finland received 210 PaK 40’s in 1943-1944. They were used to replace the existing obsolete AT guns in their inventory (like the 37mm Bofors) and were assigned at a divisional level. It was put to effective use on the Karelian Isthmus during the Soviet Summer Offensive of 1944, where it could be dug in and ranged to previously designated killing zones. The Finnish military kept the gun in service until 1986.
Finnish PaK 40 on the Summa front, 1944. Photo: SA Kuva
Other German allies such as Albania, Bulgaria, Romania, and Hungary also received small numbers of the Pak 40 guns but these were of limited use as the tides of war had turned against them and they soon found themselves surrendering before they could press any numbers of the gun into service.
The Soviet Red Army was also impressed by the performance of the PaK 40 and would often put captured versions directly into service.
In 1955 the USSR sent a small number of captured PaK 40s to North Vietnam. The North Vietnamese Army used them in a coastal defense role at the Red River Corridor until they were retired in 1972.
– Caliber: 75 mm
– Barrel length: L/46 or 3.45 m
– Rifling: 32 grooves, right-hand increasing twist, 1/24 to 1/18.
– Weight in firing position: 1,425 kilograms (the US M5 was 2,210kg, the British 17 pounder was 3,034kg and the Soviet ZiS-3 was 1,116kg)
– Height: 1.25 metres (the US M5 was 1.62m, the British 17 pounder was 1.6m and the Soviet ZiS-3 was 1.37m)
– Length with the carriage: 6.2 metres
– Length: 3.70 metres
– Width: 2.0 metres
– Traverse: 65°
– Elevation: -5° to + 22°
– Max, ROF: 14 r.p.m.
– Effective firing range: 1.8 km
– Maximum indirect firing range: 7.678 km (HE shell)
Heereswaffenamt documents give the following statistics for the penetration values of the PaK 40 (all against 60-degree angle):-
– 100 metres = 99mm
– 500 metres = 91mm
– 1000 metres = 81mm
– 100 metres = 126mm
– 500 metres = 108mm
– 1000 metres = 87mm
The standard 7.5 cm PaK 40 on its towed mount.
7.5cm PaK 40 auf Raupenschlepper Ost (RSO)
The Sdkfz. 234/4 “PaK-wagon” mounting the 7.5 cm PaK.
The Sd.Kfz.251/22 7.5cm PaK 40 L/46 auf Mittlerer Schützenpanzerwagen.
These illustrations are by Tank Encylopedia’s own David Bocquelet.
The PaK 40 remained relevant until the end of the war, being able to pierce the armor of almost any Allied tank. Its standard ammunition was the Panzergranate 39 (PzGr. 39) Armored Piercing, Capped, Ballistic Cap (APCBC) which fired at a velocity of 790 m/s, and was capable of penetrating the armor of the Soviet KV-1 tank at 500 meters. It also had the Panzergranate 40 (PzGr. 40) Armor Piercing, Composite Rigid (APCR) shell which had a tungsten core with a muzzle velocity of 990 m/s but these became more scarce as the sources of tungsten dried up.
The gun would be crewed by 5 men, but if the situation required, the entire gun could be operated by just a single soldier. The rate of fire by a trained crew was 14 rounds per minute but on average the rate of fire was a respectable 11 rpm. Each gun would form one part of a platoon (3 guns) which in turn would form one part of a battery (3 platoons). These would be motorized, towed by Sd.Kfz.7, 8 or 11’s, and supported by a signals and HQ platoons, and would be assigned at a divisional level for command and control. The normal distribution would see each platoon being attached to one of the division’s three infantry regiments.
Dug-in and camouflaged PaK 40 with a full crew in Italy 1943. Photo: Bundesarchiv
The introduction of the PaK 40 meant that the tactics of the Panzerjäger needed to be changed. Originally, the small size and mobility of the anti-tank guns allowed them to be near the front lines and their small size and lower silhouette meant they were easier to camouflage and harder to spot. The PaK 40’s 1.25 metre height made it harder to conceal and the heavyweight meant that moving it without the aid of a vehicle was laborious and slow. This forced the PaK 40 to be deployed further away from the front lines and thus be less effective in a defensive role, and it also meant it was more at risk of flanking once an enemy force broke through as it would be unsupported.
Despite all the advantages of the PaK 40, one of the biggest disadvantages was its weight, weighing in at 1,425 kilograms. This made any kind of manhandling impossible and the net result of this was many guns and crews were lost as the enemy advanced, for example, the Finns had lost 60 of their 210 guns by the end of the Soviet Summer offensive of 1944. This meant that each gun had to carefully put into position, dug in and then supported by infantry and have its tractors nearby so a quick getaway could follow if and when needed.
It remained, though, at the forefront of German defense as the Allies swept into Germany. Its lower profile in comparison to its contemporaries, coupled with the advantages of the defender, allowed it to cause many casualties amongst the armored corps of the advancing Allied forces.
The PaK 40 was seen as such a success that it saw itself turned into a tank gun, both in an unmodified and modified form. The modified form was given the designation 7.5 cm KwK 40 (7.5cm Kampfwagenkanone 40) or 7.5cm StuK 40 (7.5cm Sturmkanone 40) depending on if it was mounted into a tank or an assault gun respectively. The modification also saw its barrel length either cut down to 43 calibers or lengthened to 48 calibers.The L43 version was put into the first 120 Sturmgeschütz III Ausf.F as well as the Panzer IV from the Ausf.F2 to the first 1,200 models of the Ausf. G. The L48 version was then used on all the remaining StuG III’s, as well as all the StuG IVs. It also equipped all remaining later variants of the Panzer IV.
A Panzer IV Ausf. J of 12th SS Panzer Division “Hitlerjugend” in Belgium 1943. Photo: Bundesarchiv
It was also used in a slightly modified form on the Marder series of tank hunters. These were a solution to the issues of mobility and anti-tank performance currently lacking in the Wehrmacht. The Marder I used the captured French Lorraine 37L tractor, the Marder II used the obsolete Panzer II chassis and the Marder III was based upon the Czech Panzer 38(t). All these designs were very simple conversions to make, essentially placing the Pak 40 onto the chassis and building the fighting compartment around it. Some modification occurred, as in the PaK 40 armed Marder II’s that had a modified shield. The increased mobility allowed the Marders to keep up with Panzer units or be rushed from reserve to where they were needed. Despite having flaws, like a cramped fighting compartment, high silhouette, and limited gun traverse, these interim tank destroyers performed very well against their opponents.
During the later stages of the war, many experimental or ad-hoc anti-tank designs were produced. One of the more ‘standard’ designs was the 7.5cm PaK 40 L/46 auf Mittlerer Schützenpanzerwagen. This took the Sd.Kfz.251 half-track and bolted the PaK 40 to the top of it. In this configuration, it could take 22 rounds and gave some much needed anti-tank capability to divisional reconnaissance units. Despite being favored by those at the top (Hitler gave his approval and priority for the design in late 1944), it did suffer from being now too heavy and that the recoil of the gun was too powerful for the chassis. This meant that whilst it could sit in prearranged positions, take a shot and scoot, it was also susceptible to mechanical failure caused by the firing.
Probably the strangest use of the PaK 40 was the 7.5cm Pak 40 auf Raupenschlepper Ost (RSO). This strange little vehicle highlighted the desperate need by the German High Command for mobile anti-tank guns. The RSO was occasionally used as a prime mover for the PaK 40 and experiments were conducted to house the PaK within the vehicle itself and unload it to a position but this idea was soon scrapped due to various issues. In 1943, it was considered making a permanent fixture of the PaK 40 on a 360-degree mount and, coupled with the cross-country performance of the tractor, this made for a mobile and hard-hitting AT platform. It did see deployment on the Eastern Front in early 1944 but it did not garner a great reputation and earned the nickname of “Rollender Sarg Ost”, a play on the RSO abbreviation. It translates to “rolling coffin east”.
As mention in a previous section, Hungary was one of the countries to acquire the gun. Hungary bought the production license of the PaK 40, who would have produced the gun under the name of ‘7,5 cm 40 M. páncéltörő ágyú’. Only a handful of prototypes were manufactured before the end of the Second World War, however. Two of these were used as the main armaments of the 43M. Turán III medium tank and 44M. Zrínyi I assault gun prototypes.
Armored Vehicles Equipped With the PaK 40
– 7.5cm PaK 40 auf Raupenschlepper Ost (RSO)
– 7.5cm PaK 40 L/46 auf Mittlerer Schützenpanzerwagen
– 7.5cm PaK 40 (Sf) auf Geschützwagen FCM (f)
_ 7.5cm PaK 40/1 (Sf) auf Geschutzwagen 39H (f)
– Jagdpanzer IV
– Marder I auf Geschutzwagen Lorraine Schlepper (f)
– Marder II Sd.Kfz.131
– Marder III Sd.Kfz.138
– Panzerkampfwagen IV (Ausf. F2 onwards)
– Sturmgeschütz III (Ausf. F onwards)
– Sturmgeschütz IV
Links, Resources & Further Reading
Panzerjäger vs KV-1 Eastern Front 1941-43 by Robert Forczyk: Osprey Publishing
Volume 1 Number 11 Intelligence Bulletin July 1943 Military Intelligence Service War Department Section V pg 38- 41
German Artillery at War 1939-45 Volume 1 by Frank De Sisto: Concord Publications
Panzerjäger German Anti-Tank Battalions of World War II by W. Davis: Almark Publishing Co. Ltd.
On Panzerworld.comOn wwiiafterwwii