What determines the maximum ordinate of a round?

The maximum ordinate of a round refers to the highest point in its trajectory during flight before it begins descending toward the target. Understanding this concept is essential for effective machine gun employment, as it informs the effective range and lead necessary for targeting moving objects.

The option stating that the maximum ordinate occurs at 2/3 the distance to the target is founded on the principles of projectile motion. When a round is fired, it follows a parabolic trajectory. Given typical firing and target distances, the maximum height is reached approximately two-thirds of the way to the target as the projectile climbs, peaks, and then descends. This understanding allows for better aiming adjustments, ensuring that rounds are more likely to hit the intended target despite the effects of gravity and air resistance.

Other options that suggest variance with humidity, constant elevation, or dependency on ammunition type don't accurately capture the fundamental mechanics of projectile trajectories or their average behaviors in combat scenarios. While factors like humidity can influence ballistic performance, they do not fundamentally dictate the point at which maximum ordinate is achieved relative to the target distance in the way that the correct answer does.