This text is a transcription of the file in PDF format.
Specifically designed for the tactical, law enforcement and
committed precision shooting communities, the Viper® PSTTM
series of riflescopes offer the highest levels of performance
and reliability. With features such as matched turret/reticle
subtensions, RZRTM zero stop mechanisms and precision ranging
reticles, the Viper PSTs are ready for any situation.
The Focal Plane
All riflescope reticles can be termed either first focal plane (FFP)
or second focal plane (SFP), depending upon their internal location
within the riflescope. Many Viper PSTs are available in both reticle
First Focal Plane Reticles
First focal plane (FFP) reticles are located near the windage and
elevation turrets in front of the image-erecting and magnifying
lenses. This style of reticle will visually grow and shrink as you
change the magnification. The main advantage of an FFP reticle is
that the reticle subtensions used for ranging, holdovers, and wind
drift corrections are consistent at all magnifications. The reticle is
heavier at higher magnifications and finer at lower magnifications.
Second Focal Plane Reticles
Second focal plane (SFP) reticles are located near the scope’s
eyepiece behind the image erecting and magnifying lenses. This
style of reticle does not visually change in size when you change
the magnification. The advantage of an SFP reticle is that it always
maintains the same appearance.
For PST models using second focal plane reticles the listed reticle
subtensions used for estimating range, holdover, and wind drift
correction are only correct at the highest magnification.
Reticle Focus Adjustment
Vortex Viper PST riflescopes use a fast focus eyepiece designed to
quickly and easily adjust the focus on the riflescope’s reticle.
To adjust the reticle focus:
1. Look through the riflescope at a
blank white wall or up at the sky.
2. Turn the eyepiece focus knob in
or out until the reticle image is as
crisp as possible.
Note: Try to make this particular
adjustment quickly, as the eye will
try to compensate for an out-of-focus reticle.
Once this adjustment is complete, it will not be necessary to refocus every time you use the riflescope. However, because your
eyesight may change over time, you should re-check this adjustment
Looking directly at the sun through a riflescope, or any optical
instrument, can cause severe and permanent damage to your
The Subtension Scale: MOA or MRAD
Depending on which version you have purchased, your Viper PST
riflescope will feature adjustments and reticles scaled in MOAs or
MRADs. If you are unsure of which scale is used, reference the top
of the adjustment turret.
Both minute-of-angle (MOA) and milliradian (MRAD) unit of arc
scales are effective when ranging or adjusting riflescope for bullet
A minute of angle will subtend 1.05 inches at a distance of 100
yards. Viper PST riflescopes with MOA adjustments use ¼ minute
clicks which subtend .26 inches at 100 yards / 7.3 mm at 100
meters, .52 inches at 200 yards / 14.6 mm at 200 meters, .78
inches at 300 yards / 21.8 at 300 meters, etc.
An MRAD will subtend 3.6 inches at a distance of 100 yards. Viper
PST riflescopes with MRAD adjustments use .1 MRAD clicks which
subtend .36 inches at 100 yards / 1 cm at 100 meters, .72 inches
at 200 yards /2 cm at 200 meters, 1.08 inches at 300 yards / 3 cm
at 300 meters, etc.
Windage and Elevation Adjustments
Vortex Viper PST riflescopes incorporate
precision finger adjustable elevation and
windage dials with audible clicks.
To make adjustments:
1. Turn the adjustment knob in the
appropriate direction: Up/Down or
Left/Right as indicated by the arrows.
2. Following the directional arrows, turn
the knobs in the direction you wish the
bullet’s point-of-impact to go to.
With each click of the Viper PST moving the point-of-impact 1/4
MOA, four clicks of the knob will move a bullet’s point-of-impact
1.05 inches at a 100 yard sight-in distance. At 100 meters, four
clicks will move the point of impact 29.1 mm.
With each click of the Viper PST moving the point-of-impact .1
MRAD, four clicks will move the bullet’s point-of-impact 1.44 inches
at a 100 yard sight-in distance. At 100 meters, four clicks will move
the point-of-impact four centimeters.
Image Focus and Parallax Correction
Select Viper PST riflescopes feature a side focus knob which
should be used to fine-tune the image focus. When the image is
sharply focused, parallax error will also be eliminated.
Using the Side Focus
1. Be sure the reticle is correctly
(see Reticle Focus section on page
2. Turn the side focus knob until the
target image is as sharp as possible.
The yardage numbers referenced
on knob should closely match the
actual yardage to the target.
3. Check for parallax error by moving your head back and forth
while looking through the scope. The focus is correct if there is
no apparent shift of the reticle on the target. If you notice any
shift, adjust the focus knob slightly until all shift is eliminated.
Parallax is a phenomenon that results when the target image
does not quite fall on the same optical plane as the reticle within
the scope. This can cause an apparent movement of the reticle
in relation to the target if the shooter’s eye is off-centered.
Correctly focusing the target image will allow it to fall on the
same optical plane as the reticle within the riflescope.
Vortex Viper PST riflescopes incorporate Vortex’s patented Radius
Bar to visually assist in keeping track of elevation turret rotations.
The radius bar provides a quick visual reference that allows the
shooter to confirm:
• Knob orientation is
correct and has not shifted
as a result of accidental
• By watching the position
of the bar while making
elevation adjustments, the
shooter is able to quickly
track full, half and quarter
Variable Power Adjustments
To change magnifications, turn the magnification
ring to the desired level.
The Vortex Viper PST riflescopes use
a variable intensity reticle illumination
system to aid in low light performance.
To activate the illumination, rotate the
adjustment knob in either direction.
The illumination knob allows for 10
levels of brightness intensity; an off click
between each level allows the shooter
to turn the illumination off and return
to a favored intensity level with just one
Replacing the Battery
1. Unscrew the outer cap with a coin.
2. Remove the battery.
3. Replace with a new CR 2032 battery.
4. Re-install the outer battery cap and be sure to
fully tighten it down.
RZR Zero Stop
Vortex Viper PST riflescopes incorporate the RZR Zero Stop feature.
After the rifle is sighted in, the RZR Zero Stop allows fast, sure
return to the original zero point when large multi-revolution elevation
corrections have been dialed into the riflescope.
Without a zero stop, the shooter must pay very careful attention
when dialing large corrections needing multiple revolutions of
the elevation knob. If the shooter loses track of the number of
revolutions, the original zero point may become lost. Because of the
RZR Zero Stop, the elevation knob on Vortex Viper PST scopes can
be quickly spun back to the original zero without having to carefully
Once the RZR Zero Stop is set, the elevation knob will stop turning
at the original zero point when being returned from a temporary
elevation correction. Learn how to adjust the RZR Zero Stop in the
Boresighting and Range Sight-in sections on pages 12-15.
Initial boresighting of the riflescope will save time and money at the
range. This can be done by removing the bolt and sighting through
the barrel on a bolt action rifle, or using a mechanical or laser boresighter.
1. Begin by turning the elevation turret clockwise until it stops. No initial
preparation is needed on the windage
2. Loosen, but do not remove, the
three elevation turret cap retaining
3. Lift the elevation turret cap up and
off the turret body. This will reveal the
inner turret with marked scale to be
used for sight in.
4. Next, loosen, but do not remove,
the three elevation zero stop lock
screws on the inner turret.
5. If using a mechanical or laser boresighter, set up according to manufacturer instructions.
6. Using the inner turret scale for elevation reference, make windage and elevation adjustments until the reticle crosshair is aligned
with the adjustment pattern, target or laser dot.
Note that you will not feel “clicks” as the elevation knob is adjusted—this is normal. The “clicks” will return after final zero stop is set
at the rifle range.
After rifle is boresighted, do not re-tighten elevation zero stop lock
screws on inner turret or replace the outer turret cap. This will be
done after the final range sight-in is complete.
Range Sight-in and RZR Zero Stop Set
Once the riflescope has been boresighted, final sight-in and RZR
Zero Stop set should be done at the range shooting the same
ammunition expected to be used in the field. 100 yards is the most
common zero distance, although a 200 yard zero may be preferred
for long distance applications. As previously noted in the section on
Boresighting, the outer elevation turret cap should be removed and
zero stop lock screws on inner turret should be loose.
1. Be sure to follow all safe shooting practices.
2. Before shooting, be sure the reticle and side focus are properly
set (see Reticle Focus Adjustment pg. 6, Image Focus pg. 8).
3. At your preferred zero distance, fire a three-shot group as
precisely as possible.
4. Next, adjust the reticle to match the approximate center of the
shot group (see section on Windage and Elevation Adjustment). If
the rifle is very solidly mounted and has not shifted you can simply
look through the scope and adjust the reticle until it is centered on
the fired group.
5. Carefully fire another three-shot group and see if the bullet group
is centered on the bullseye. Repeat process until group is centered
in desired spot.
6. Gradually tighten the three inner
turret zero stop lock screws in an
even pattern until firmly tight. If
using torque wrench, tighten screws
to approximately 8 in/lbs.
7. Replace elevation turret outer cap, being sure to align “0” mark
on cap with the zero reference line on scope body. Push the cap
straight down and avoid rotating while doing this. Be sure the cap is
8. Gradually tighten the three outer elevation cap retaining screws
in an even pattern until firmly tight. If using torque wrench, tighten
screws to approximately 8 in/lbs.
9. Check to be sure the zero stop
is correctly set – elevation turret
should not be able to rotate in
Note: After setting, if zero stop does rotate clockwise or if you wish
to re-zero a different load, repeat complete boresighting and range
sight-in procedures. It is very important to always begin any sight-in
adjustments by turning elevation turret clockwise until fully stopped.
Re-Indexing Windage Turret After Sight In
1. Loosen the three windage turret cap retaining screws and
carefully pull the windage turret cap straight off.
2. Replace windage turret cap, aligning the “0” mark on cap with
the zero reference line on scope body. Push the cap straight down
and avoid rotating while doing this. Be sure the cap is fully down.
3. Gradually tighten the three retaining screws in an even pattern
until firmly tight. If using torque wrench, tighten screws to
approximately 8 in/lbs.
The fully waterproof and fogproof Vortex Viper PST riflescope
requires very little routine maintenance other than periodically
cleaning the exterior lenses. The exterior of the scope may be
cleaned by wiping with a soft, dry cloth.
When cleaning the lenses, be sure to use products, such as the
Vortex Fog Free cleaning products or Lens Pen, that are specifically
designed for use on coated optical lenses.
• Be sure to blow away any dust or grit on the lenses prior to
wiping the surfaces.
• Using your breath, or a very small amount of water or pure
alcohol, can help remove stubborn things like dried water spots.
All components of the Vortex Viper PST riflescopes are permanently
lubricated, so no additional lubricant should be applied.
Note: Other than to remove the turret caps, do not attempt to
disassemble any components of the riflescope. Disassembling of
riflescope may void warranty.
If possible, avoid exposing your Vortex riflescope to direct sunlight or
any very hot location for long periods of time.
The VIP Warranty
We build optics based on our commitment to your absolute
satisfaction. That’s why Vortex products are unconditionally
guaranteed and we make this Very Important Promise to you—a Very
Rest assured that in the event your Viper PST becomes damaged
or defective, Vortex Optics will repair or replace the riflescope at
no charge to you. Call Vortex Optics at 800-426-0048 for prompt,
professional, and friendly service.
2120 West Greenview Drive
Middleton, WI 53562
The VIP Warranty does not cover loss, theft, deliberate damage
or cosmetic damage that does not hinder the performance of the