During the firing cycle, what component is depressed when the trigger is pulled on the MK19 machine gun?

The receiver sear is the component that is depressed when the trigger is pulled on the MK19 machine gun. This action is crucial because the receiver sear acts as a safety mechanism that holds the firing pin in a retracted position until the trigger is activated. When the trigger is pulled, it disengages the sear from the firing pin, allowing the firing pin to move forward under the influence of its own internal spring. This movement strikes the primer of the cartridge, leading to the firing of the round.

Understanding the function of the receiver sear is essential for operating the MK19 safely and effectively. It ensures that the weapon cannot fire unintentionally and provides the operator with control over the firing sequence. The other components mentioned do not directly engage with the trigger action in the same way, emphasizing the specific role of the receiver sear in the firing cycle.