ASh-12.7

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 environment 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 FSB late in 2011.

Overview
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 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 variety of bullets. Ammunition for ASh-12.7 is based on the 12.7×55mm straight-walled, rimless brass case, originally developed by same organization for silenced VKS sniper rifle. Standard loading for ASh-12.7 is a lightweight, supersonic bullet with an aluminum core, exposed at the front and hollowed at the rear. It is partially enclosed into bi-metal jacket. Bullet weight for STs-130 cartrige is 48,14-76,08 gramm, muzzle velocity is 290–315 metres per second. It have several loadings with light, heavy and duplex load with two light bullets.

This new Russian ".50-caliber" cartridge bears certain conceptual similarity to a family of big-bore cartridges, developed in the US for the AR-15 platform, such as .499 LWR or .50 Beowulf, although Russian cartridge uses longer case. STs-130 12.7×55mm cartrige have bullet with weight -  48,14-76,08 gramm, while its US counterparts usually are loaded with bullets weighing 19 grams/300 grs and up.

The ASh-12.7 assault rifle itself is of a bullpup layout, with stamped steel receiver and polymer housing/stock. It is believed to use a gas operated, rotary bolt action. Firing controls include two separate levers – fire mode selector (Semi/Auto) at the rear and ambidextrous safety (Safe/Fire) above the pistol grip. There are several configurations of the basic rifle. First one features integral carrying handle with built-in rear diopter sight and folding front sight. A length of the Picatinny rail is installed on the carrying handle to accept various optical sights. Another version that was observed on some photos features "flat top" configuration with Picatinny rail running atop of the receiver, and rear and front sights installed on folding bases. Other variations include either a Picatinny rail below the forend or an 40mm underbarrel grenade launcher. Muzzle devices include a muzzle brake or quick-detachable silencer.