The German 3.7 cm Pak was a iniquitous anti-tank gun in the first half of the war. After the Germans faced the T-34 and KV-1 tanks in the summer of 1941 it was nicknamed Panzeranklopfgerät or Tank Knocking Device due to its inability to penetrate their armour. However, this penetration table shows that the gun was a tad more potent than its reputation suggests.
The text begins in the same way as other manuals of this type, with a general description of how to fight enemy tanks and a legend. The blue marking represents the armour piercing shell, the green marking is the subcaliber shot, and the yellow is a high explosive shell. On the tank, the black is areas where shooting is effective, hatched areas can result in some effect, and white areas are immune.
Since the manual was published in 1942, it is no surprise that the Red Army has Matilda tanks. The Germans were well familiar with them after the Battle of France in 1940. Unfortunately for them, they established back then that the 3.7 cm Pak was not very effective against this type of tank. Firing APCR at the front can be effective at close range against the driver's visor and front tip of the hull. Hitting the sides and rear of the turret with APCR can also be effective. When firing AP, the gunner's only hope was to hit the narrow opening in the spaced armour protecting the side of the tank. HE could also be used to hit the rear and set the engine on fire.
The Valentines were not a secret either, nor was the fact that their armour was slightly thinner than the Matilda's. A gunner lucky enough to have APCR on hand could fire it at the front, rear, or side from 150 meters. A lack of vulnerable openings like the Matilda had made AP shells ineffective. As before, landing an HE shell in the right spot could set the tank on fire.
Now we get to the T-34. With APCR, the gunner has similar options to when engaging the Matilda. The driver's hatch, hull machine gun, and gun mantlet are vulnerable from the front. A thin strip where the turret armour is near vertical could also result in a penetration from 100 meters. From the side, the turret could be penetrated at 100 meters, and the lower hull could be penetrated at 200, if the gunner managed to land a shot between the wheels. The radiator intakes on the engine deck, rear area where the turret bustle hangs over the engine deck, and exhaust pipe covers are also shown as vulnerable areas. Unlike the Matilda and Valentine, the Germans have not figured out how to set this tank on fire with HE.
Despite the KV-1's thicker armour, it's essentially just as vulnerable as the T-34. APCR can be used to penetrate the front, sides, or rear at close range. The gun mantlet, driver's vision port, and hull machine gun are vulnerable. Like the British tanks, it can be set on fire by shooting the ventilation opening in the back.
The KV-1 with applique armour (KV-1 reinforced, in German parlance) offers a more difficult target. The parts with extra armour are completely immune to the 37 mm gun, even with APCR. The rear can be attacked in the same way. It's interesting to note that the Germans still give the weight of this tank as 44 tons, even though tanks of this type could weigh as much as 50 tons.
Even though the KV-2 would have been nearly extinct by then, it is included in the manual anyway. The vulnerabilities of this model are essentially the same as those of its lighter cousin. The gunner is advised to fire APCR at any vertical armour at a range of 100 meters, try to hit the gun mantlet, vision port, and hull machine gun, and set the engine on fire with a lucky shot to the rear.