Which cycle of operation of the M9 pistol occurs after the round is fired, causing the barrel and slide to move rearward?

The cycle of operation that occurs after the round is fired and causes the barrel and slide to move rearward is known as the unlocking phase. In this phase, the energy generated by the fired cartridge causes the slide to move backward, allowing the barrel and slide to separate. This action is critical because it facilitates the extraction of the spent cartridge casing from the chamber and prepares the firearm for the next shot.

During unlocking, the locking mechanism that secures the barrel to the slide during firing is disengaged. This process ensures that the spent case can be properly ejected and a new round can be chambered in subsequent steps of the cycle. It reflects the M9 pistol's operational design, ensuring reliable function after firing a round.

The other processes—extracting, loading, and feeding—occur after unlocking or in conjunction with the unlocking phase but do not specifically describe the movement of the barrel and slide in response to firing a round. For instance, extracting refers to the removal of the spent casing, while loading involves bringing a new round into the chamber. Feeding typically describes the action of placing a round into the chamber from the magazine. Understanding the distinction between these phases is crucial for comprehending the overall functioning of the M9 pistol.