KS-23

The KS-23 (Karabin Spetsialniy-23, "Special Carbine 23") is a Soviet pump-action weapon developed by TsNIITochMash for the Ministry of Internal Affairs and officially classed as a carbine in Russia because its barrel is rifled. Firing a 23 mm shell, it is the largest-bore shotgun in modern use - equivalent to roughly 6.3 gauge by British and American measure, or about 4 gauge under current European CIP tables. Design work began in 1971 and the weapon was accepted for police use in 1985.

Its unusual calibre is the result of a deliberate economy. The barrels were taken from the Gryazev-Shipunov GSh-23, the 23x115mm autocannon fitted to Soviet combat aircraft; barrels rejected by quality control for aircraft use were judged perfectly adequate for the far lower stresses of firing slugs and less-lethal rounds. These were cut down for the KS-23 and a 23x75mm shell developed around them, which is why the weapon is a rifled shotgun. It was issued to MVD forces including the Militsiya and the Internal Troops from the mid-1980s, primarily for suppressing prison riots.

The ammunition family reflects that role. Alongside the "Shrapnel-10" and "Shrapnel-25" buckshot rounds, effective to 10 and 25 m respectively, there is "Barrikada", a solid steel projectile able to disable a car engine block at up to 100 m; "Volna-R" rubber and "Strela-3" plastic less-lethal bullets; the "Cheremukha-7" CN and "Siren-7" CS tear gas grenades; the "Zvezda" flash-bang; and the PV-23 blank for launching grenades. Two add-on muzzle mortars, the 36 mm Nasadka-6 and the 82 mm Nasadka-12, extend the range of gas grenades further.

The original KS-23 has a 510 mm barrel, an overall length of 1,040 mm, a three-round underbarrel tube magazine plus one in the chamber, and an effective range of 150 m. The KS-23M "Drozd", accepted after trials that concluded in December 1991, shortens the barrel to 410 mm and replaces the fixed wooden stock with a detachable wire buttstock, giving 875 mm with the stock and 650 mm without. The KS-23K of 1998 adopts a bullpup layout and, addressing the main criticism of the tube-magazine models - that ammunition could not be changed or replenished quickly - feeds from a detachable seven-shell box magazine, at the cost of a shorter 100 m effective range. A smoothbore civilian version, the TOZ-123 Selezen-4 in standard 4 gauge, has been sold in Russia since 1996. Users include Russia's FSB Border Guard Service, the Armenian police, Kazakh prison guards, the Uzbek customs service, Ukraine and North Korea.