| Bullpup assault rifle|
| Federal Security Service|
The ASh-12.7 (АШ-12.7, which stands for "Автомат штурмовой 12.7мм" or "Automatic assault rifle, 12.7mm") assault rifle is a dedicated CQB/Urban Operations weapon, developed by TsKIB SOO ("Central Design and Research Bureau of Sporting and Hunting Arms"), a subsidiary of the KBP Instrument Design Bureau of Tula, Russia, by request from the Russian FSB (Federal Security Service). The weapon is intended for special units of the FSB which operate in urban environments against heavily armed and organized gangsters and terrorists. According to the Russian press, the first batch of ASh-12.7 assault rifles was delivered to the FSB in late 2011.
The ASh-12.7 is a dedicated "Close/Urban combat" weapon for high-risk law enforcement operations, which must combine high stopping power with limited penetration and a short 'dangerous range', to avoid collateral damage to innocent bystanders or hostages. To achieve these goals, the designers of the ASh-12.7 assault rifle developed special large-caliber ammunition, loaded with a variety of bullets. Ammunition for the ASh-12.7 is based on the 12.7×55mm straight-walled, rimless brass case, originally developed by the same organization for the silenced VKS sniper rifle. Standard loading for the ASh-12.7 is a lightweight, supersonic bullet with an aluminum core, exposed at the front and hollowed at the rear and partially enclosed into a bi-metal jacket. The cartridge has a bullet weight of 48.14-76.08 grams and a muzzle velocity of 290–315 metres per second. It has several loadings; light, heavy and a duplex load with two light bullets.
This new Russian ".50-caliber" cartridge bears certain conceptual similarities to a family of big-bore cartridges developed in the US for the AR-15 platform, such as .499 LWR or .50 Beowulf, although the Russian cartridge uses a longer case and generally a heavier bullet load - its US counterparts are usually loaded with bullets weighing 19 grams/300 grs and up.
The ASh-12.7 assault rifle has a bullpup layout, with a stamped steel receiver and a polymer housing/stock. It is believed to use a gas operated, rotary bolt action. Firing controls include two separate levers; a fire mode selector (Semi/Auto) at the rear and an ambidextrous safety (Safe/Fire) above the pistol grip. There are several configurations of the basic rifle. The first one features an integral carrying handle with a built-in rear diopter sight and a folding front sight. A length of Picatinny rail is installed on the carrying handle to accept various optical sights. Another version that was observed on some photos features a "flat top" configuration with a Picatinny rail running on top of the receiver, as well as front and rear sights installed on folding bases. Other variations have a Picatinny rail below the fore end or a 40mm underbarrel grenade launcher. Muzzle devices include a muzzle brake or a quickly-detachable suppressor.