A Ukrainian M1152A1 HMMWV (High Mobility Multipurpose Wheeled Vehicle) belonging to the 1st. Air Force Combined Rifle Brigade fitted with a Gryazev-Shipunov GSh-23 23mm twin-barrel autocannon.
The GSh-23 first entered service in 1965 and was designed as a armament for fighter aircraft. It was the primary gun armament for late model Mikoyan-Gurevich MiG-21 fighters (NATO reporting name Fishbed) and all versions of the later MiG-23 (NATO reporting name Flogger) among other aircraft. It is also used in some models of the Mil Mi-24 helicopter (NATO reporting name Hind), notably the Mi-24VP, Mi-24VM, and Mi-35M (export variant of the Mi-24V).
Designed by the KBP Instrument Design Bureau, the GSh-23 uses a Gast principle action. The action works in that the recoil of one barrel firing loads and charges the second barrel. When the second barrel fires, it loads and charges the first. This permits a high rate of fire with the GSh-23 able to reach 3,400 rounds per minute. Empty, the weapon has a weight of 108 pounds.
The GSh-23 can fire a wide range of 23X115mm ammunition. Two of the more common types are the OFZ which is a HEI (High-Explosive Incendiary) round and the BZ-A which is a API (Armor-Piercing Incendiary) round. The OFZ carries a .7 of an ounce A-IX-2 explosive payload and uses either an AG-23 or AG-23D fuze. The BZ-A is a solid shot round with a incendiary filled ballistic cap. When firing on ground targets, the effective maximum range is just under 1 mile (.9 of a mile). The BZ-A round, at 200 meters, is able to penetrate 10mm of RHA (rolled homogeneous armor). As such, it is only much of a threat to soft skinned vehicles and very lightly armored vehicles.
Primary Sources:
https://kintex.bg/product-4-293
https://web.archive.org/web/20230201163056/http://www.russianammo.org/Russian_Ammunition_Page_25mm.html#8
