Proper aiming is very important in case of this ammunition.
However, they don't damage most of the modules, only a direct hit will temporary deactivate them. AP bullets deal high damage (usually twice as much as high explosive ammunition) and have higher penetration. It is used less frequently, only in specific situations. Second type is armor piercing ammunition. The lower it is, the more often you should use HE ammunition. Your cannon's caliber is very important as well. The armor is set there under such angle that the HE bullets will ricochet.
High explosive ammunition should be also used when shooting at the bow (front) or the stern (back) of the warship. On such distance you have low chance to penetrate the armor, but you can set enemy on fire or destroy some important module. Most of all, it should be used when shooting from long distance. HE ammunition is used in few specific situations. An effective high explosive fire can destroy even much stronger opponent.
