Mounting a noise/flash suppressor and using a modified standard round with reduced-velocity bullet shows a sufficiently simple and convenient way for converting standard-issue military firearms into noiseless weapons. However, basic items of weapons and rounds are usually developed without due regard to silent fire requirements. Therefore special development of "firearm-cartridge" systems more fully meeting specific requirements for such firearms was the new step made in noiseless weapon evolution.
The BSK noiseless sniper system was developed at the TSNII TOCHMASH Research Institute (Klimovsk) by P. I. Serdyukov and V. F. Krasnikov and adopted for service in 1987. The BSK system includes a special sniper rifle (VSS Vinforez. index 6P29) and a special 9 mm round (SP 5, index 7N8).
The SP 5 sniper cartridge was developed by N. V. Zabelin and L. S. Dvoryaninov on the basis of the mod. 1943 cartridge case- its bullet is in a bimetallic jacket and has a steel core with a lead-filled cavity behind it. The heavy subsonic bullet remains stable on the trajectory providing good accuracy of fire and penetration effect. Firing with the SP. 6 round with enhanced penetration effect bullet is also possible. Shot noise level does not exceed that of small-bore sporting rifle. The weapon is characterized by comparatively quiet action and firing mechanisms, while impacts of metal components in standard-issue firearm provided even with efficient noise suppressors are the typical revealing factor.
The VSS rifle is a gas-operated weapon using powder gases vented from the barrel bore and a long-stroke piston rigidly attached to the receiver The weapon is locked by a rotating bolt with six locking lugs engaging sockets cut in the receiver. The receiver is machined from steel to provide more rigid structure compared with a stamped one. The recoil kick perceived as relatively soft improves accuracy of fire.
The striker-type firing mechanism with light firing pin also improves accuracy of fire. The main spring of the striker is set lower than the recoil spring behind the bolt. The non-automatic safety switch is of lever type. Separate fire mode selector is placed inside the trigger guard behind the trigger, its right position corresponds to the single-shot fire mode, and left — to the automatic fire mode.
When shot is fired, powder gasses go into the integrated silencer through the holes drilled in the bottoms of the grooves in the wall of the relatively short barrel (before the gas discharging port), and through the muzzle. As the shot continues and the bullet moves along the barrel bore, powder gasses enter into the silencer cylinder. The cylinder has a separator placed before the muzzle. The separator has holes in the end cups and in slant baffles for bullets to pass. Bullets pass through the holes without touching the cups and baffles while powder gasses collide with the latter, change their direction, and lose velocity and temperature. The silencer mounts an open ramp-type rear sight and front sight.
The silencer is easy to detach and disassemble for cleaning, but firing from the rifle without silencer is not allowed.
A fixed frame-type wooden stock is provided with an elastic heel.
The receiver is provided with a rail on its left wail for brackets to mount optical or night sights. The VSS rifle is fitted with the PSO-1-1 sight or a night sight. The PSO-1-1 sight is similar to the PSO-1 sight of the SVD sniper rifle but has ranging scales compliant with the SP. 5 and SP. 6 ballistics. Fire at night can be conducted with the use of the NSPU-3 magnifying sight, 1PN75, MBNP-18 (for the VSSN rifle), impact dispersion diameter for 10-shot series fired from the VSS rifle in the single-shot fire mode with the SP. 5 round at a range of 400 m must not exceed 11 cm.
For concealed carrying the rifle is easily dismantled into major parts: silencer, stock, receiver with barrel and firing mechanism. The magazine is of box type, with plastic body and staggered arrangement of 10 rounds.