The gun is the module which acts as a vehicle's main armament. Guns can fire a variety of ammunition types and have varying characteristics with regards to accuracy, penetration ability, reload time and damage. These characteristics can be different on different vehicles, or on the same vehicle in different turrets. If a gun is damaged in battle it will receive an accuracy penalty, and if the gun is destroyed it will not fire or move until repaired.
A vehicle's gun is affected by its gunner(s) and loader(s) (a tank can have more than one gunner or loader). The skill of the gunner(s) being used will affect the accuracy and aiming characteristics of the gun, while the skill of the loader(s) will affect its reload times. Having either knocked out in battle will result in a severe accuracy or reload penalty accordingly. If a gunner has the "armorer" skill trained, the gun will receive less of an accuracy penalty when damaged than it would normally.
Guns by nation