The PK is a 7.62 mm general purpose machine gun designed in the Soviet Union and currently in production in Russia. Its NATO equivalents are the FN MAG, MG3, and M60 machine guns. The PK machine gun was introduced in the 1960s and replaced the SGM and RPD machine guns in Soviet service. The PK machine gun can be used as a light anti-aircraft weapon when it is put on an AA mount. One feature typical to Soviet machine guns is that the standard model feeds from the right and ejects its rounds via an ejection port on the left side of the weapon, as opposed to the usual right side ejection port seen in most western machine guns.The original PK (Kalashnikov Machine gun) was a development of Kalashnikov\'s automatic rifle design, firing the 7.62x54mm Eastern Bloc standard ammunition originally from the Mosin-Nagant. It is equipped with a simple bipod and is designed as a squad-level support weapon also suitable for installation and vehicle mounting. Most are belt-fed, using linked 25 round belts. These 25 round belts can be linked to any length necessary.The current model is the PKM (Kalashnikov Machine gun Modernized), a modernized, product-improved version of the PK. It is just 7.5 kg empty and the PKMS version on the light Stepanov tripod weighs only 12 kg. For heavier employment, the PKMS model features a more stable tripod mounting. A special PKMSN2 model fits modern NSPU night sights for low visibility operations. PKT (PK Tank) is a further development of PK to replace the SGMT Goryunov vehicle mounted machine gun. Modifications include removal of stock, longer and heavier barrel, added gas regulator and electric solenoid trigger.The PKM and other variants are in production in Russia and currently are exported to many nations. Over 1,000,000 copies have been manufactured. Additionally, various models are manufactured locally around the globe. Zastava Arms produces the PK under license as the M84 (along with the PKT as the M86), and it remains in use with many of the former Yugoslav successor states. The most recent modification is the Russian Pecheneg, which features a forced air cooling barrel that cannot be removed in the field for quick replacement, unusual for a modern machine gun.