What is the first step in the immediate action for an M9 that fails to fire?

When an M9 pistol fails to fire, the initial response is to ensure the magazine is properly seated. This action is crucial because a common cause of failure to fire is an incorrectly seated magazine, which can lead to a malfunction such as a feed issue. By confirming that the magazine is securely in place, the shooter can eliminate this potential problem before moving on to more drastic measures.

Ensuring the magazine is properly seated sets the stage for the subsequent actions and helps in diagnosing the problem accurately. If the magazine isn't seated correctly, even if all other components are functioning properly, the weapon will not fire. Once it's confirmed that the magazine is correctly seated, the shooter can then proceed to other troubleshooting actions if necessary, such as racking the slide or conducting remedial action if the problem persists.

Other choices, while important in handling malfunctions, come into play after confirming the magazine seating. This step is foundational for ensuring that the firearm can operate effectively.