ACOG

The ACOG sight provides a magnification of 4.0x. It can be attached to any weapon with a rail or an RIS adapter equipped.
 * The sight can be assigned to a quick access hotkey for quick attachment and detachment, even while aiming down sights.

On the left side of the reticle, there is plenty of information that can be used to accurately hit the target at longer distances. To take a reading and display the information, press the left-ctrl button once.
 * The information displayed is as follows (from top-left to bottom-right):

The intelligence based sniping skill can be increased at character creation or through practice, to decrease the amount of time it takes to get a reading.
 * RNG: Range - The distance between you and the target.
 * WND: Windage - The direction and speed of the wind. (A reading of "E LOW" would imply a slow wind speed in an eastern direction)
 * TMP: Temperature - Air temperature at the location of the shooter.
 * HUM: Humidity - The percentage of humidity in the air at the location of the shooter.
 * PRS: Pressure - Barometric pressure at the location of the shooter.
 * ALT: Altitude - The altitude of the target, relative to the shooter.

On the right side of the reticle are the adjustments set by the player.
 * X4: Magnification - Non-adjustable on this sight. Fixed at 4.0x.
 * ZERO: Vertical Adjustment - To be used with the RNG reading. Adjusted with shift-mousewheel.
 * WNDG: Horizontal Adjustment - To be used with the WND reading. Adjusted with shift-alt-mousewheel. Positive values adjust right, negative values adjust left.

Weapon Compatibility
 No RIS Adapter Required RIS Adapter Required
 * M16A4 * MK18 * SVD
 * AK-47 * AKM

Known Issues

 * When switching optics via quick access hotkey while ADS, the magnification level will not change until you leave ADS and return.