The most effective trajectories to target the brainstem include aiming from the back of the skull at the base of the neck (suboccipital region) with a direct trajectory inward following the axis of the spinal column, behind the ear by placing the shot immediately in the mastoid region and angling slightly diagonally toward the center of the skull, or from inside the mouth by inserting the barrel into the mouth and aiming upward toward the soft palate at an angle that passes through the base of the skull and reaches the brainstem. Extreme precision is essential as the brainstem is a small structure protected by robust bones.