When firing the M9, what happens after the last bullet is fired?

When the last bullet is fired from the M9, the slide locks back. This mechanism serves a critical function in indicating to the operator that the magazine is empty and that it’s time to reload. When the magazine runs out of ammunition, the slide, which houses the barrel and recoil spring, is forced to its rearmost position and locks in place. This not only prevents inadvertent firing of the weapon but also provides a clear visual and tactile cue that action is needed to reload. The locking back of the slide is a standard feature in many semi-automatic handguns, including the M9, to enhance user awareness and safety during operation.