Operation Manual

Elevation
Knob
Windage
Knob
45
Vortex Viper PST riflescopes incorporate precision finger
adjustable elevation and windage
dials with audible clicks.
Windage and Elevation Adjustments
Depending on which version you have purchased, your Viper
PST riflescope will feature adjustments scaled in MOAs or
mrads. If you are unsure of which scale is used, reference the
top of the adjustment turret.
1. Turn the adjustment knob in the
appropriate direction: Up/Down
or Left/Right as indicated by the
arrows.
2. Move the knobs in the direction
you wish the bullet’s point-of-
impact to change.
To make adjustments:
If the adjustment is in MOAs,
the turret will display
“1 Click = ½ MOA”.
If the adjustment is in mrads,
the turret will display
“1 Click = .2 mrad”.
Both minute-of-angle (MOA) and milliradian (mrad) unit of
arc scales are effective when using subtension measurements for
ranging and bullet trajectory drop compensation in reticles.
MOA or MRAD
MRAD Adjustments
Example: With each click of the Viper PST moving the point-of-impact
.2 mrad (.72 inches), four clicks will move the bullet’s point-of-impact
2.88 inches at a 100 yard sight-in distance. At 100 meters, four clicks
will move the point-of-impact eight centimeters.
Example: With each click of the Viper PST moving the point-of-impact
1/2 MOA, it will take four clicks of the knob to move a bullet’s point-of-
impact 2.10 inches at a 100 yard sight-in distance.
MOA Adjustments
Mrad unit of arc measurements are based on the radian. A
radian is the angle subtended at the center of a circle by an
arc that is equal in length to the radius of the circle. There
are 6.283 radians in all circles and 1000 milliradian in a
radian for a total of 6283 milliradians (mrads) in a circle. An
mrad will subtend 3.6 inches at a distance of 100 yards. The
Viper PST 1–4x24 riflescope with mrad adjustments use
.2 mrad clicks which subtend .72 inches at 100 yards, 1.44
inches at 200 yards (4 cm at 200 meters), 2.16 inches at 300
yards (6 cm at 300 meters), etc.
MOA unit of arc measurements are based on degrees and
minutes. There are 360 degrees in a circle, 60 minutes in a
degree for a total of 21,600 minutes in a circle. A minute of
angle will subtend 1.05 inches at a distance of 100 yards. The
Viper PST 1–4x24 riflescope with MOA adjustments use
1/2-minute clicks which subtend .52 inches at 100 yards, 1.04
inches at 200 yards, 1.56 inches at 300 yards, etc.