The effects of wind vary depending on changes in wind speed and direction. Wind is classified by the direction it is blowing in relationship to the firer/target line. The clock system is used to indicate wind direction and value (Figure F-8, page F-8). Winds that blow from the left (9 o'clock) or right (3 o'clock) are called full-value winds, because they have the most effect on the bullet. Winds that blow at an angle from the front or rear area are called half-value winds, because they have about one-half the effect on the bullet as full-value winds. Winds that blow straight into the firer's face or winds that blow straight into the target are termed no-value winds, because their effect on the bullet is too small to be concerned with.
Figure F-9, page F-8, illustrates how the effects of wind on the bullet are similar to the effects of gravity—as range increases, the effects of wind increase.
A 10-mph full-value wind moves an M16A1 (M193) bullet about 1/2 inch at 25 meters to about 46 inches at 475 meters. (Using the data presented, wind effects for all
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