What should the gunner do first when setting up a range card for a machine gun?

When setting up a range card for a machine gun, the first action the gunner should take is to lay behind the gun and set the sights on the grazing fire limit. This step is crucial because it establishes the effective range at which the weapon will be used to engage targets. By determining the grazing fire limit, the gunner can ensure optimal positioning for both direct and indirect fire engagement, enhancing the weapon's effectiveness in combat scenarios.

This process involves aligning the sights with the area of expected engagement while also considering the terrain and potential enemy movements. It allows the gunner to focus on the immediate battlefield environment, ensuring that the machine gun is set up for maximum impact.

In contrast, other options, such as recording the maximum range or verifying the unit location on a map, are important tasks but do not directly influence the immediate setup of the machine gun for effective firing. Walking the final protective line (FPL) might occur later in the process but is not the priority step to take first when establishing the range card. By prioritizing the grazing fire limit, the gunner ensures that the main objectives of engaging targets effectively and efficiently are achieved from the start.