What is the term used when the heat of the barrel causes the propellant powder inside the round to ignite even if the primer hasn't been struck?

The term "cook off" refers to a situation where the heat generated in a firearm's barrel causes the propellant inside a round to ignite without the firing mechanism, such as the primer, being struck. This phenomenon typically occurs when a weapon has been subjected to prolonged firing, which increases the temperature of the barrel to the point that the heat can ignite the propellant.

In a "cook off" scenario, the round may fire unexpectedly after the weapon has been heated up, posing significant risks to the operator and others nearby due to the uncontrolled discharge. Understanding this concept is crucial for firearm safety and operational procedures within the Fleet Marine Force, as it underscores the importance of monitoring barrel temperatures during sustained fire scenarios to prevent unintended discharges that could lead to accidents or injuries.

Other terms like "hang fire," "misfire," and "chain fire" describe different issues related to firearm operation and ammunition, such as delayed ignition or multiple rounds firing unintentionally. However, they do not accurately capture the specific situation where the heat from the barrel causes a round to ignite on its own.