Military movies often depict nighttime firefights illuminated by streaks of colorful light–tracer rounds. But these glowing projectiles have a more complex purpose than just visual spectacle.

In this article, we’ll dig beyond the Hollywood portrayal and explore five surprising facts about tracer rounds and their use in the US military.

1) A Tracer Glows When Shot

Tracer Rounds machine gun
Machine gun tracer rounds illuminate the sky during an attack by militants in the Pesh Valley in Afghanistan’s Kunar Province. (Photo by Tim Wimborne/Reuters)

As Britannica explains, tracer rounds contain a pyrotechnic compound that ignites during flight, creating the signature glowing trail. But the purpose of these rounds goes beyond a light show.

There are two main reasons for using tracers:

Target Correction: Tracers help soldiers adjust their aim by making bullet trajectories visible. This is especially crucial in low-light conditions or for suppressing fire, where the goal is to keep enemy heads down rather than achieve pinpoint accuracy.

Psychological Warfare: In rare instances, tracers may be used to create the illusion of overwhelming firepower, potentially discouraging the enemy from continuing the fight.

However, tracer rounds come with a significant drawback: they reveal the shooter’s position.

This is particularly dangerous for individual soldiers whose camouflage and concealment are vital. A bright tracer streak can easily guide enemy fire back to its source, potentially putting the soldier at risk. This trade-off between target correction/suppression and position disclosure is why tracer rounds are typically used sparingly, often mixed with regular ammunition.