76-mm Regimental Gun Ob-25 technical Details
- Years of production-1943-1946
- Total issued-5,152 units.
- Caliber-76 mm
- Weight in combat position-600 kg
- Barrel length-1480 mm
- Length of the threaded part-1214 mm
- Payment – 6 people
- Driving speed-35 km / h
- Rate of fire-10-12 rounds/min
- Maximum firing range-4200 m
- Direct shot range-400 m
- Horizontal – 60°
- Vertical – 8° +25°
76-mm Regimental Gun Ob-25 Details
In 1943, with the transition of the Red Army to strategic offensive operations, the discrepancy between the characteristics of the 76-mm regimental gun of the 1927 model of the year and the requirements of the front was visibly revealed. The question of creating a more mobile and light regimental cannon with large horizontal firing angles and increased targeting speed was very acute. Back in 1942, OKB-172 (Perm) under the leadership of M. Y. Tsirulnikov (where a 45-mm M-42 anti-tank gun was created shortly before) developed a preliminary design of a new gun.
Tsirulnikov, using a repeatedly tested method, proposed to impose a 76-mm barrel with weak ballistics on the carriage of a 45-mm anti-tank gun of the 1942 model of the year. Such a solution made it possible to obtain a fairly light artillery system that uses well-developed elements in production, at the same time, it did not meet the requirements of the GAU for a 1942 regimental gun, which required a higher initial velocity of the projectile compared to the 1927 model gun. As a result, in 1942 this project did not arouse much interest on the part of the State Agrarian University. However, the cessation of work on other regimental guns, with the simultaneous appearance of 76-mm rounds with a cumulative projectile , which made it possible to hit enemy tanks with an armor protection thickness of up to 70 mm, regardless of the initial velocity of the projectile and the firing range, forced the GAU leadership to reconsider its attitude to the OKB-172 regimental gun project.
The design of the OKB-172 regimental gun received the factory index OB-25 and already in February 1943, plant No. 172 began to manufacture and test prototypes.
The OB-25 was designed according to the classical scheme and consisted of a monoblock barrel with a screw breech and a piston bolt (similar to the bolt of a 76-mm regimental gun of the 1927 model) and a carriage with tubular sliding frames from a 45-mm anti-tank gun, but with minor changes to increase the strength of its components and mechanisms, which compensated for the increase in the mass of the sliding parts of the gun.
The carriage consisted of: upper and lower machine tools with frames, anti-recoil devices (hydraulic recoil brakes and spring-type knurler) placed in the cradle under the barrel, shield cover, combat course with spring-type springing, lifting and turning mechanisms of the sector type. The shield cover, designed to protect the crew from bullets, small fragments and shock waves from close explosions, consisted of upper and lower shields. The height of the firing line was 718 mm . On the upper machine were mounted sighting devices-a mechanical sight from a cannon of the 1927 model of the year and an artillery panorama of the Hertz system. Metal wheels of automobile type ZIK-1 (with spokes) or GAZ-AA (disk type), with bullet-resistant tires, filled with sponge rubber.
The gun kit included a front end with a charging box, borrowed with minor alterations from the 45 mm anti-tank gun. In the stowed position, the gun was transported by mechanical or horse traction at speeds up to 35 km / h .
The ammunition package included unitary shots with a steel fragmentation or cast-iron high-explosive fragmentation grenade, shrapnel and buckshot, as well as with a cumulative projectile. Shots fired at the OB-25 cannon were not interchangeable with shots fired from any other Soviet 76-mm guns; the cannon had its own ballistics specially developed for it. In June of the same year, a prototype of the OB-25 gun was handed over for field testing. After eliminating a number of shortcomings, in July 1943, military tests followed, and already on September 4, 1943, the gun was adopted by the Red Army under the official name “76-mm regimental gun of the 1943 model of the year” with the simultaneous cessation of production of the regimental gun of the 1927 model of the year.
Compared to its predecessor, the 1943 model regimental gun significantly benefited in mobility and horizontal guidance angle up to 60° (which gave better opportunities for maneuvering fire and fighting tanks), but with the same rate of fire, it was much inferior in maximum range (up to 4200 m ) and accuracy of fire. With weaker internal ballistics, the specific muzzle energy of the new gun decreased by almost 1.5 times compared to this value for the 1927 model gun (355 and 516 J/kg, respectively). Firing from the new gun could only be carried out on a reduced charge.
The 1943 model regimental gun entered service with artillery batteries of rifle and cavalry regiments (4 guns each), as well as artillery divisions of separate mechanized and rifle brigades (4 guns each). A certain number of these guns were transferred for arming the Troops of the Polish and Czechoslovak military formations on the territory of the USSR.
The 1943 model regimental gun, due to its low combat weight, turned out to be an exceptionally maneuverable fire support device for infantry, capable of operating directly in the battle formations of rifle units, quickly hitting firepower and infantry groups, destroying field-type fortifications, repelling sudden enemy counterattacks from a place, without additional training, and, if necessary, destroying medium and light tanks, as well as other armored vehicles with cumulative ammunition. Production of the 76-mm regimental gun of the 1943 model was organized at the end of 1943 at the plant
No. 172, where 4,164 guns of this type were manufactured up to and including 1945. Since 1944, the plant No. 106 was connected to its production. Molotov cocktail (Khabarovsk). Production of the gun was completed in 1946, a total of 5,152 guns were produced.