What distinguishes the PKM from the PK series rifles?

The distinguishing feature of the PKM compared to the PK series rifles is its heavier and longer barrel combined with a stamped receiver. The PKM was designed to be a more robust and durable machine gun, which is essential for sustained fire in combat situations. The heavier barrel allows for better heat dissipation during prolonged firing, reducing the risk of overheating and maintaining accuracy over extended periods. Additionally, the stamped receiver contributes to the overall lightweight design of the PKM, making it easier to manage in the field while still providing the structural integrity needed for a machine gun.

This combination of a heavier, longer barrel and the use of a stamped receiver is significant in enhancing the weapon's performance, especially in terms of reliability and firepower. The enhancements make the PKM distinct, setting it apart from the PK series rifles, which were designed as general-purpose rifles and do not possess these specific features.