How does the use of tracer rounds benefit machine gunners in combat?

The use of tracer rounds provides a significant advantage to machine gunners by allowing for instantaneous visual feedback on the trajectory of their fire. This visibility enables gunners to adjust their aim more effectively based on where the tracer rounds impact, facilitating quicker corrections for windage, elevation, and target movement. The glowing trail of the tracer rounds serves not only as a guide for the shooter but also helps to communicate to teammates the approximate line of fire, which is crucial in dynamic combat situations.

In contrast, increasing the velocity of rounds or reducing the weight of ammunition does not pertain to the unique function of tracer ammunition. Similarly, while tracer rounds can be used against vehicles, they are not specifically designed for that purpose and do not enhance effectiveness against them in the way they aid in aim and accuracy. Thus, the primary and most beneficial aspect of tracer rounds lies in their ability to enhance the gunners' targeting abilities through visible feedback.