2A28 Grom

The 2A28 Grom is the main armament of the BMP-1 and BMD-1 infantry fighting vehicles. It is a 73 mm low pressure smoothbore semi-automatic gun with a wedge breech block. Development of the 2A28 Grom was directly linked to that of the SPG-9 recoilless gun; both fired projectiles similar to rocket-propelled grenades.

During the early 1960s, the Soviet Armed Forces issued a requirement for a new infantry transporter that was highly mobile, sufficiently armed to destroy comparable Western vehicles such as the M59 and the Schützenpanzer Lang HS.30, and allowed embarked infantrymen to fight from within its crew compartment. This concept evolved into the BMP-1.

The BMP was initially to be armed with a 23mm autocannon, a choice directly inspired by the success of the West German HS.30. However, the Soviet government had invested heavily in the development of anti-tank guided missile (ATGM) systems and discussion soon shifted to arming the BMP with missiles. This would allow it to defend itself against main battle tanks. The KB Priborostroyeniye design bureau in Tula soon proposed a specialized turret carrying both a low-velocity smoothbore gun and a mount for 9M14 Malyutka ATGMs. The purpose of the gun was to destroy tanks at closer ranges where the missiles were largely ineffective.

The gun is relatively compact and weighs 115 kilograms (254 lb). In the BMP, the gun is brought to bear by an electric motor, with a manual mechanical backup. The maximum horizontal and vertical traverse speed with the electrical system is 20 °/s and 6 °/s respectively. Minimum horizontal and vertical direction rate is correspondingly 0.1 °/s and 0.07 °/s. The gun can be depressed and elevated between −4° and +33°, with aimed fire possible up to an elevation of +15°. The turret can traverse 360°. Cyclic rate of fire is between 8 and 10 rounds per minute, with the gun returning to an elevation of +3° 30' to reload after each shot if the autoloader is used.

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