Unlike the AKM and RPK the PK machine gun series is an open bolt design, which improves heat management during automatic fire compared to closed bolt designs and helps avoiding the dangerous phenomenon known as "cook-off", wherein the firing chamber becomes so hot that the propellant contained in a chambered round unintentionally ignites, making the weapon fire until the ammunition is exhausted. Open bolt designs typically operate much cooler than closed bolt designs due to the airflow allowed into the chamber, action and barrel during pauses between bursts, making them more suitable for constant full-automatic weapons such as machine guns. General-purpose machine guns like the PK are further normally issued with several quick change barrels that during prolonged intense use are swapped out allowing one barrel to cool while the machine gun fires with the other.