Armor-Piercing ammunition is used solely in standard and light autocannons. It was first prototyped by the Federated Suns in 3053, with full production beginning in 3059. AP ammo uses advanced ballistics materials and improved anti-armor warheads, allowing them to punch through otherwise fresh armor and damage internal systems. However, their increased weight negatively affects the weapon's accuracy and allows for less ammunition to be stored.
In game terms, AP ammo suffers a +1 to hit modifier and an ammo bin carrying AP ammunition can only carry half as many rounds (round down). The advantage is that it gains a critical hit chance anytime it strikes an enemy unit, even without damaging the internal structure, though it suffers a negative modifier to the roll that becomes more detrimental as the size of the autocannon gets smaller.
- TechManual, p. 208, "Autocannon Munitions - Armor-Piercing Ammunition"