Which components are part of the M240's operating system?

The components part of the M240's operating system include the bolt, operating rod, gas piston, and barrel. These parts work together to facilitate the weapon's operational cycle.

The bolt is crucial as it is responsible for feeding, chambering, and extracting cartridges. The operating rod plays a vital role in the weapon's cycling action, transferring the energy from the gas piston to cycle the action. The gas piston harnesses the gas generated from burning gunpowder to drive the operating rod. Finally, the barrel is the component through which the bullet is propelled.

Together, these components ensure the M240 functions effectively, managing everything from firing to cycling the next round, making them essential elements of the operating system.

Other options may include important parts of the weapon but do not encompass the core elements that directly interact during the firing process and operate the action. For instance, while the trigger is vital for firing and the magazine is necessary for ammunition storage, they do not directly function as part of the operating system in the same manner as the components listed in the correct answer.