Tracer Ammo is a free ammo attachment that adds tracers ammo in intervals of standard ammo. The frequency of tracer rounds increase if a magazine is close to empty. Tracer ammo can also be used to indicate to friendly forces where you are shooting and also helps with suppression. Insurgent forces use green tracers and Security forces use red tracers.
Tracer ammo performs in the exact same manner as standard ammo, damage and penetration wise. The damage model used for tracer ammo is the same as the one used for standard ammo. In Insurgency, only certain weapons can equip tracer ammunition: light Machine Guns come preloaded with Tracer ammo and cannot be removed, even when equipping AP or HP, while shotguns and handguns cannot equip tracer ammunition.