Ammo Options

Ammunition Options (also known as Ammo Options) is an enhancement to piercing attack advantages (think: a gun built into a character sheet).
Your attack – which must do piercing damage – can switch between different types of ammunition. Switching is a free action at the beginning or end of your turn. If it takes you a full turn to select between ammo types, add a flat -5% to the final value of this enhancement. 
You may only choose one of the options below. Each enhancement is restricted to attacks that do a certain type of piercing damage. This is to avoid an impossible situation; e.g., a huge piercing attack can’t have HP Ammo, because there’s no way to increase the damage type by a step!
Attack Type 	Armor-Piercing	Hollow-Point	Multi-Ammo
Small Piercing (pi-)	-- 	+40% 	--
Piercing 	+20% 	+20% 	+40%
Large Piercing (pi+)	+45% 	+20% 	+65%
Huge Piercing (pi++)	+35% 	-- 	--
== In Layman's Terms ==
Armor Piercing works like AP ammo in other weapons in the game--converting the damage down one step (e.g., piercing to small piercing) but giving a (2) armor divisor.
Hollow-Point works the opposite way, increasing the damage type one step (e.g., piercing to large piercing), but reduces armor penetration to (0,5).
== References ==
Power-Ups 4: Enhancements, p.18