What marks the end of the distance recording process for the range card?

The end of the distance recording process for the range card is marked by the loss of grazing fire due to terrain. This is significant because grazing fire is a type of fire where the bullets travel in a flat trajectory and can effectively engage targets at a designated range. When the terrain changes to an extent that causes the loss of this effective engagement capability, it indicates a limitation to the feasible range for accurate fire. Consequently, noting this constraint is vital for proper range card development, as it ensures that the gunner understands the effective engagement zones and any potential obstructions that could impact fire support.

The other options, while relevant in the context of machine gun employment, do not specifically indicate that the distance recording process should cease. For example, achieving maximum firing capability or changing positions might influence tactics but do not directly denote the completion of distance recording. Similarly, completing three distance recordings is a procedural step, but losing grazing fire due to terrain is a definitive factor that impacts the placement and potential effectiveness of fire, thus marking the conclusion of the distance recording process.