"Battle Stations! Battle Stations! All hands, man your Battle Stations!!!"... ??
~Or~ did you tell him to shoot at something? There is a difference between manning the gun, and shooting the gun.
The "skill level" of a gunner is broken down into his skills with "guns", his "watchman" ability, and his "leadership". You don't care as much about his "electrical" there, so choose gunners wisely.