At what point does the M2 reach the cook-off stage?

The M2 machine gun reaches the cook-off stage after a burst of 250 rounds or more. This phenomenon occurs due to the heat generated from the continuous firing, which raises the temperature of the barrel and the chamber to a level where the ammunition can ignite without an external source of ignition.

When firing in rapid succession, the metal of the barrel absorbs and retains heat. At around 250 rounds, the heat accumulates to a critical point where it can cause the propellant in the cartridges to ignite due to the high temperature. This understanding is crucial for maintaining safety and preventing unintentional discharges caused by overheating while operating the weapon system.

The other options suggest different round counts or continuous firing durations that do not align with the established threshold for cook-off conditions for the M2. Specifically, the threshold of 250 rounds is derived from extensive testing and operational experience, ensuring operators are aware of their firing limits to maintain safety.