What is a unique feature of the Kalashnikov series of rifles?

The unique feature of the Kalashnikov series of rifles is its gas-operated, rotating bolt design. This mechanism is integral to the rifle's operation and is a distinguishing characteristic that contributes to its reliability and ease of use in a variety of conditions. The gas-operated system utilizes the gas generated by a fired cartridge to cycle the action, allowing for semi-automatic or fully automatic firing modes depending on the model. Additionally, the rotating bolt design enhances locking strength and ensures that the rifle can function effectively despite dirt, debris, or adverse environmental conditions, which is one reason for its widespread adoption and use in many military forces around the world.

Other mechanisms like lever-action, spring-loaded magazines, or revolving cylinders do not pertain to the Kalashnikov rifles, emphasizing the significance of the gas-operated, rotating bolt mechanism as its defining feature.