Angle Cosine Indicator.

Author:Fortier, David M.

If you're a serious rifleman who demands the utmost from both your rifle and yourself this is a simple piece of gear you should know about. Designed by Ward Brien, the Angle Cosine Indicator is an aid for practical and tactical rifle shooters when engaging elevated or depressed targets. Under such conditions if the angle of the shot isn't taken into account a rifleman will overshoot his target. The Angle Cosine Indicator is designed to give you the angle cosine so you can quickly and easily correct for gravity's effect on your bullet's trajectory.

A simple yet rugged instrument, it's manufactured from aircraft grade aluminum and anodized either green or black. It mounts easily to your scope's tube via a standard scope ring. The face of the instrument has a dial showing the correct cosine for whatever angle the weapon's bore is pointed at. As the rifle is elevated or depressed the dial rotates.

In use the operator first ranges his target conventionally. Then, while aiming at his target he reads the cosine number shown on the ACI. The actual range is then multiplied by this cosine (example: 442 yards X .82...

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