During which process does a cartridge leave the barrel after the shot?

The firing process is when a cartridge leaves the barrel after the shot is initiated. During this phase, a firing pin strikes the primer of the cartridge, igniting the propellant within. This explosion generates high-pressure gas that propels the bullet forward through the barrel and out into the air.

Throughout the firing sequence, the other processes mentioned do not involve the bullet leaving the barrel. Chambering refers to the action of loading a new cartridge into the chamber, extracting involves pulling the spent cartridge case from the chamber after firing, and locking pertains to securing the bolt in place to allow for safe firing. Thus, the firing process is indeed the correct answer as it directly correlates with the bullet's exit from the barrel following ignition.