BPK-76 76-mm Kurchevsky dynamo-reactive gun

In order to compensate for the pressure of powder gases and reduce recoil, it was necessary to equip artillery guns with heavy gun carriages, strong barrels and various recoil devices. In contrast to this, the Russian engineer D. Ryabushkin, in 1916, offered for testing a completely new type of cannon, which was an ordinary tube on a tripod. The principle of its operation was simple: the powder gases, which threw the projectile out of the muzzle, partially went out through the opposite opening, reducing the recoil to a minimum.

Beginning in 1923, research and development work was carried out in the USSR to create dynamo-reactive (recoilless) guns (DRP). The basis of these works was the scheme of LV engineers. Kurchevsky and S.A. Isenbek, in which in the breech of the gun there was a conical nozzle. When fired, the projectile in the DRP, as in a conventional artillery gun, accelerated when moving along the barrel channel by the force of pressure of powder gases on its bottom. At the same time, the expelling charge gases exited not only through the muzzle, but also through the breech, equipped with a nozzle, part of the barrel. The gases that went through the breech created cravings that balanced the recoil force. Thus, in a recoilless gun, the gun carriage was not affected by any significant efforts, and it could have a lightweight design. However, it differs favorably from the classical artillery systems by a small mass.

Intensive research led to the creation in 1930 of the first cannon of the DRP-4 Kurchevsky system. In 1932, the Special Design Bureau No. 1 of the Red Army Directorate of Art was created under the direction of L.V. Kurchevsky, at the disposal of which entered the plant number 38 in the village. Podlipki (Moscow region).

At the end of 1931 L.V. Kurchevsky created his most famous weapon, which was to become the main means of direct support for infantry in the battalion-regiment. It was adopted by the Red Army by the Decree of the Revolutionary Military Council in August 1932 under the designation “76-mm Kurchevsky battalion cannon” (BOD-76). An important advantage of this gun compared to conventional 7b-mm field guns was its low weight, in the combat position - only 180 kg, which was almost eight times less than the mass of the 76-mm gun of the 1902/30 model. The calculation of 4 people could conduct intense fire, it is easy to move the BOD-76 over rough terrain on their own.

Among its shortcomings were: a small range of fire, a strong sound of a shot and a powerful jet of gases that raised a cloud of dust, unmasking a weapon.

The BPK-76 gun consisted of a barrel, a light two-wheeled gun carriage and sighting devices. The barrel-monoblock of this gun, made ribbed to improve heat transfer during firing, had a bolt with a central nozzle block mounted on the thread. The slope of the rifling in the bore is constant. When loading, the shutter moved along with the nozzle block. Charging was made from the breech. Screw lifting mechanism. Screw worked on the lever, mounted on the right axle. The swivel mechanism is also of screw type. The gun had a panoramic sight with a drum, equipped with two scales. The tubular welded two-wheeled carriage was a light tubular welded frame with a front coulter and a trunk to support the trunk in a combat and field position. The hedgehook was located next to the vomer. The combat drive was a bound wooden wheel on a steel axle without suspension, which excluded the towing of a gun by a car. Transportation BPK-76 carried horse riding.

For shooting from the BPK-76 cannon, 76-mm unitary shots from three-inch guns with shrapnel, high-explosive fragmentation and armor-piercing grenades were used, but their shells differed from standard openings - at the bottom and on the walls, from which after ignition, gunpowder gases flowed out. The holes in the sleeve were closed with wooden or cardboard traffic jams. The thickness of the cardboard for the cork in the side opening was 6 mm, and at the bottom - 4 mm. The projectile had a leading belt located at the bottom, which, when it moved in the bore, was easily deformed. The greatest firing range of the frag grenade was 7000 m. The transfer time from the traveling position to the combat one took 47 seconds.

One of the features of the gun was the ability to use it as a mortar for firing 76-mm finned shells at a fixed angle of 45 ° at a distance of 250 to 1000 m. At the same time, a nozzle was removed from the bolt and a device in the form of a shortened sleeve with a sting was inserted into the barrel chamber. The process of loading and firing was similar to the shooting of a conventional muzzle-loading mortar. The 76-mm recoilless gun BPK-76 could easily be mounted on trucks and cars and even on motorcycles, which sharply increased its maneuverability on the march and in battle. On the basis of the BPK-76, a gun for PDA boats and a self-propelled SU-4 were created, which was a recoilless weapon installed in the back of a GAZ-AA truck. The quick-detachable pedestal, on which the gun was mounted, provided firing - both from the body and from the ground.

The serial production of BPK-76 was organized at three plants: No. 7 named after Frunze (Leningrad), No. 8 named after Kalinin (settlement Podlipki, Moscow Region) and Bolshevik (Leningrad). With a total order of 959 BPK-76 in three factories from 1932 to 1935, 487 guns were manufactured. By November 1, 1936 in the Red Army consisted of 407 guns BPC-76. The Kurchevsky gun was decommissioned in 1939, and all work on recoilless guns was curtailed.