How a PP-19 BIZON works

The Bizon (English: Bison) is a 9mm submachine gun developed in 1993 at Izhmash by a team of engineers headed by Victor Kalashnikov (son of engineer Mikhail Kalashnikov, creator of the AK-47 and AK-74). Alexei Dragunov, youngest son of Evgeny Dragunov (the creator of the SVD sniper rifle), was also a member of the design team.

The Bizon was developed at the request of the Ministry of Internal Affairs (MVD) and is primarily intended for counter-terrorist and law enforcement units that usually need fast and accurate fire at close ranges. Prototypes were trialed by the Special Equipment Research Institute in 1995 where they outperformed several competitors, and the weapon was accepted into service on December 28, 1996. The Bizon is issued to armed response units of the Federal Security Service (FSB) and Ministry of Justice. It was used in combat operations against separatists in the volatile North Caucasus region, namely Chechnya and Dagestan.

The Bizon is a lightweight selective fire weapon that fires from a closed bolt, a feature that enhances the gun's accuracy. It is based on the AKS-74 and features a 60% parts commonality with the assault rifle. Chambered for the standard Russian 9×18mm Makarov pistol cartridge, the gun will also fire a new high-impulse armor-piercing 57-N-181SM round.

The Bizon uses a simple straight blowback method of operation; an unlocked breech system reduces cost and build complexity. The Bizon's operating cycle is characterized by a very short recoil stroke; standard 9×18mm ammunition will only drive the bolt partially to the rear of the receiver and results in a cyclic rate of 700 rounds/min. High-impulse ammunition drives the bolt all the way to the end of the receiver, lightly striking the receiver wall. A rate of fire of 650–680 rounds/min is the result. This has the effect of reducing perceived recoil and increasing firing stability and hit probability.

The Bizon has no gas system and the internal components have been modified accordingly. The bolt carrier with integral charging handle was recycled from the AK, but the piston rod and rotary bolt were removed and the piston extension was plugged with a steel insert. The return spring and guide rod are identical to those of the AK.

The Bizon has a four-groove barrel with a 240 mm (1:9 in) right-hand rifling pitch. The gun's muzzle device has a large rectangular port on each side of dead center that serves to reduce muzzle jump, although the main purpose of this device is to protect the muzzle and magazine from damage.

The pinned and riveted sheet metal receiver of the Bizon is derived from the AKS-74 and has been modified at the front end, since the gas system was omitted. The handguard is a sheet metal stamping with three rectangular ventilation slots on each side. The magazine serves as the lower handguard and the current models of the magazine are ribbed to enhance grip. The Bizon also shares the same trigger and safety mechanisms of the AK-74 rifle. The selector lever is placed on the right side of the receiver, above the trigger, and has three settings: the uppermost "safe" setting disables the trigger and in this position the lever physically blocks the bolt's integral retracting handle; the middle position (marked "АВ") enables fully automatic fire and the lowest position ("ОД") will activate the semi-automatic function of the trigger.[6] An original five-piece anti-bounce device is built into the trigger unit and this functions as a rate reducer, delaying firing until the bolt has settled entirely into battery.

The Bizon also utilizes the AKS-74 shoulder stock. It folds to the left side of the receiver but unlike the AKS-74 and AKS-74U, it is not held closed by a spring-loaded capture in the forward end of the receiver. Instead, it is held closed by the forward trunnion pin which is longer on the Bizon than on its AKS-74 predecessors. The extended length of the pin allows it to catch the folding skeleton stock. The pistol grip is identical to the grip on the AK-100 series and is made of a black fiberglass-reinforced polyamide.

One of the Bizon's more unusual features is the magazine, which is often mistaken for a grenade launcher. The cylinder below the barrel is in fact a 64-round helical-feed magazine, similar to the type used in the American Calico M960 submachine gun. The magazine is made from a durable glass-reinforced polyamide and mounts under the handguard in line with the barrel. This layout makes the weapon more compact and concealable. All cartridges are aligned nose forward in the Bizon magazine and cannot be loaded incorrectly. Early magazines were fabricated from aluminium tubing and had a capacity of 67 rounds. The production magazine capacity of 64 was selected as 64 is a multiple of 16, and 9×18mm Makarov rounds are packaged in boxes of 16. The magazine has hooks on top of the front end that engage a pair of pins under the front sight, and the rear end of the magazine interfaces with a Kalashnikov pattern spring-loaded paddle type magazine catch/release located in front of the trigger guard Some magazines were produced with indicator holes allowing the user to verify the amount of ammunition loaded; these are spaced at 4, 24, 44 and 64-round increments.

The sighting arrangement resembles that used on the AKS-74U and consists of a rear flip-up sight permanently attached to the receiver top cover with two open square notches with 50 m and 100 m elevation settings and a round post front sight taken from the AK series of rifles, common to many Russian small arms. The front sight is contained in a protective hood with a hole in the top to insert an elevation adjustment tool, while the rear sight is shielded by two metal ears.

The gun is issued with one magazine, a sling, cleaning kit, oil can and magazine pouch. Other accessories such as scope mounts, Kobra optics and PBS1 sound suppressors were available due to it being largely derived from the AK-74/47 family, thus having the correct thread and AK optics side mount.