After reading the wind and distance to target, the slope angle of fire is one of the least understood and equally important variables of long range shooting. Whether shooting up or down at a target, the bullet will impact high due to the cause and effects of gravity.
The latest aid for snipers and practical field shooters who must engage elevated or depressed targets, the Angle Cosine Indicator (ACI) still requires the shooter (or, more likely, his spotter/observer) to perform a calculation. The ACI attaches to the shooter's scope, minimizing the possibility of breaking cheek-weld and losing sight of the target.
Solidly constructed, the ACI is made from aircraft grade aluminum and is available in anodized olive drab or black. The ACI is the design of Ward Brien, former U.S. military servicemen with design contributions by his partner Ping Lee.
When properly mounted and the rifle is elevated or depressed, the ACI (with the cosign numbers in five degree increments) bypasses the angle and, instead, indicates the corresponding cosine number of the angle of the elevation or depression. The shooter or his observer/spotter need only multiply the actual range by the cosine number to get the adjusted range. Having done so, the shooter adjusts the elevation on his scope and engages the target. If he has done everything correctly, including compensating for wind (which works along the actual distance of the shot), the shot should be dead on target.
Use the ACI!
It's quick, easy to use, easy to install, extremely rugged and unaffected by weather.
NOTE: Mounting requires the use of a claw-type scope ring, such as a Leupold MK IV or others.
Ring not included.
|Angle Cosine Indicator Ordering|