## Range Determination

Range determination is the process of finding the distance between two points. In most situations, one of these points will be the observer's own position. The other point may be a target or prominent terrain feature. THE ABILITY TO DETERMINE RANGE ACCURATELY IS A KEY SKILL NEEDED BY THE GUNNER TO ACCOMPLISH HIS MISSION. Not only does the accurate determination of range affect his marksmanship, but it is also required in the reporting of information and the adjustment of artillery and mortar fire. (See Table 5-1.)

There are several methods of determining range, including measuring distance on a map, pacing the distance between two points, estimating range, using an optical rangefinder, and using registration fire. However, the gunner does not usually have a map, and he rarely has access to an optical rangefinder. He can pace the distance between two points if the enemy is not within range. Firing rounds just to determine the range is not desirable since it may reveal the SAW position to enemy observers. Most of the time, the gunner must use techniques that require no equipment and that can be used without exposing himself or revealing his position. There are two methods of determining range that meet these requirements: the lOO-METER-UNIT-OF-MEASURE method and the APPEARANCE-OF-OBJECTS method.

a. lOO-METER-UNIT-OF-MEASURE METHOD. To use this method, the gunner must be able to visualize a distance of 100 meters on the ground. For ranges up to 500 meters, he determines the number of 100-meter increments between the two points he wishes to measure. Beyond 500 meters, the gunner must select a point halfway to the target, determine the number of 100-meter increments to the halfway point, and then double it to find the range to the target.

During training periods, gunners must become familiar with the effect that sloping terrain has on the appearance of a 100-meter increment. Terrain that slopes upward gives the illusion of longer distance, and observers have a tendency to overestimate a 100-meter increment. Terrain that slopes downward gives the illusion of shorter distance. In this case, the observer's tendency is to underestimate a 100-meter increment and thus underestimate the range.

600 ) METERS J