After the end of the Second World War, a large number of captured weapons and equipment fell into the hands of the Soviet military. On the basis of some of them, the USSR is beginning to develop its own analogs. Thus, the captured 75mm PaK 41 anti-tank gun interested Soviet military specialists, first of all, with its cylindrical-conical barrel shape and armor penetration. The development of a similar Soviet weapon with a caliber of 76.2 / 57 mm began to be dealt with by the Central Artillery Design Bureau since 1946. The anti-tank gun is called the S-40 and is classified as a regimental anti-tank gun.
Device and design
The lower part (carriage) for the new gun is taken from the ZIS-S-8 anti-tank gun developed in 1944, caliber 85mm. Small changes are made to the carriage. The barrel, due to its conical shape, had 76.2 mm caliber in the greater part (breech) and 57 mm caliber in the smaller part (muzzle). The length of the cylindrical-conical barrel was 5.4 meters. The charging chamber for the new gun was taken from an 85mm anti-aircraft gun, model 1939. After the chamber, the threaded conical part of 76.2mm caliber with a length of 3.2 meters began. She had 32 constant-slope rifling (22 gauge). The muzzle received a nozzle with a cylindrical-conical channel. The section of the conical smooth nozzle was 51 centimeters long, and the section of the cylindrical nozzle was 59 centimeters long. The gun receives a wedge vertical breechblock and a mechanical semiautomatic copier type. Aiming angles - (-5 + 30) degrees vertically, (± 25) degrees horizontally. The S-40 does not have a cannon front end; bed mounts were used for transportation. The suspension of the wheel travel is torsion bar, the maximum speed of transportation on the equipped road is up to 50 km / h. The total weight of the S-40 is 1824 kilograms. The deployment / folding of the gun in time was about 60 seconds. Firing speed up to 20 rds / min.
S-40 anti-tank gun ammunition
Armor-piercing sub-caliber and high-explosive incendiary tracer shells were chosen as the main ammunition for the gun. The subcaliber armor-piercing projectile had a length of 84 centimeters and a mass of 6.3 kilograms. The armor-piercing core (25mm) weighed a little over half a kilogram. Powder weight 2.94 kilograms. All this provided the projectile with a high flight speed (initial 1330 m / s), a sufficient effective firing range of up to 1500 meters and incredible armor penetration for this caliber:
- at a distance of 0.5 kilometers, the projectile penetrated when it hit 285mm of armor protection;
- at a distance of 1 kilometer, the projectile penetrated when it hit 230mm of armor protection;
- at a distance of 1.5 kilometers, the projectile penetrated when it hit 140mm of armor protection.
OFZT ammunition had a length of 89 centimeters and a mass of 9.3 kilograms. The mass of the projectile is 4.2 kilograms, the mass of the explosive projectile is 105 grams. The mass of the propellant charge is 1.3 kilograms, the flight speed is up to 783 m / s.
Comparison of C-40 and PaK 41
The Soviet analogue of the 7, 5 cm RAK-41 cannon (Grabin system) surpassed the captured sample in terms of ballistics and armor penetration characteristics, for comparison: at a distance of 0.5 km, the German gun penetrated armor up to 200mm (C-40 up to 285mm).
The fate of the S-40 anti-tank gun
The built prototype of the S-40 gun was successfully fired at factory and field trials in 1947. Accuracy and armor penetration of sub-caliber armor-piercing ammunition was higher than that of the tested 57mm ammunition of the ZIS-2 anti-tank gun. But OFZT ammunition was inferior to fragmentation ammunition (ZIS-2) in terms of effectiveness (fragmentation action). In 1948, field tests of the S-40 continue. But, unfortunately, due to the low survivability and high complexity of the barrel manufacturing technology, the S-40 anti-tank gun did not enter service with the regimental artillery.
