Kalashnikov PK

The PK (Pulemyut Kalashnikov) is the standard light machine gun of the Russian military. It is a chambered for 7.62-mm cartridge, and a gas-operated, belt-fed, sustained-fire machine gun. The Russians designed it based on Kalashnikov assault rifle. In the 1960s the PK machine gun was introduced, replacing the SGM and DP guns in the erstwhile Soviet forces. One unique feature of it is that on the left side of the weapon, the standard model ejects its rounds via an ejection port, unlike the usual right side ejection port.

A number of countries use this weapon, including two elite Israeli Special Forces. It is the choice of the armed groups in Asia and Africa. The base PK model is bipod-mounted, containing 100-round belt carried in a box fastened to the right side of the receiver. It weighs 9 kg, 1,161 mm in length, built by a mixture of stamped metal and forged steel. The PK series feed and fire at cyclic rate of 650 rounds per minute and a practical rate of fire of 250 rounds per minute with a muzzle velocity of 825m/s.

The PK has a rotating bolt type similar to the AK bolt with two locking lugs. The bolt of PK is larger and robust, with a big face to accommodate a 7.62 mm rimmed round and a claw extractor.

On the bolt carrier the firing pin is temporarily fixed, and the PK fires from an open bolt. The firing pin is easily taken away with the bolt. However when the bolt is rotating along its carrier, the firing pin remains locked on the bolt carrier. It will target and hit a primer while the bolt rotates to engage on the locking lugs. The bolt carrier resembles an AK slide, except it is positioned upside and down. It is larger, stronger and less complicated shape-wise. The PK has a long stroke piston and the gas piston is mounted on the bolt carrier and moves with it. For better corrosion resistance, the gas piston and its rod are chrome-plated, and pivoted on the bolt carrier. The hinge permits for slight bending of the carrier or gas piston while it is removed or installed.

On the barrel, the gas block is permanently mounted and attached to the gas tube through the gas regulator. Exhaust type, 3-position regulators are found in infantry versions. Using a cartridge or empty case as a tool, the gas regulator can be adjusted. The Russian reviews mention that theoretical cycle rate is 650 rpm. There is no buffering device, which is mandatory for higher cyclic rates, increasing the cyclic rate with regulator settings is not advisable for the health of the receiver, operating parts, and the gun's longevity. The PKT and PKB version have different Venturi gas regulators that do not exhaust fumes to the vehicle interior.

The receiver is U-section assembled by rivetings and weldings, stamped from 1.5mm sheet metal. The receiver contains double walls created from two 1.55 mm plates welded on upon another. The receiver top cover is imprinted from sheet steel and hinged at front to the receiver and locked at the back with a spring-loaded latch. The ejector resembles the AK's and gripped inside the receiver. The ejection port is situated at left side on receiver through which the PK ejects empty cases. On the front of the receiver, similar to the AKM, the barrel extension is wrapped. The gas piston tube and the quick-change barrel locking system are mounted on barrel extension.

The barrel distinguishes the PK and the new variation, the PKM. The PK possess heavier, fluted barrel, whereas the PKM barrel is lighter. The barrels of the armored models PKT/PKTM and PKB/PKBM are heavier for the sustained fire role. The mounted PK on a lightweight tripod is the PKS, which uses 200/250 round-belt. The tank-mounted version of the PK is the PKT, which has a longer and heavier barrel. The PKM is an improved and lighter variation of the PK.