Vortex Optics VIPER XBR 2.5-10X44 CROSSBOW SCOPE - Manual (Page 12)

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Correcting for Arrow Drop
After building your own MOA drop chart, you can correct for arrow drop by
using either the reticle or the elevation turret correction method.
Arrow Drop Correction Using the Reticle
Compensating for arrow drop and wind drift using the reticle is quick and
easy, and has a big edge in hunting situations because no game spooking
hand motion is required. Simply choose your hold point on the reticle based
on the range and your MOA drop chart and then shoot.
Using a reticle for arrow drop and wind drift compensation has one
important limitation. In second focal plane scopes, such as the Viper XBR,
reticles using drop lines are sensitive to magnification. The marked MOAs
on the XBR-1 reticle are only correctly marked with the scope set at the
highest magnification (10x). At 5x, actual MOAs will be twice what is
marked on reticle; at 2.5x, actual MOAs will be four times what is marked
on the reticle.
Using the following technique, the XBR-1 reticle will allow you to shoot
effectively with your reticle at magnifications of 2.5x, 5x and 10x.
• If you are shooting with the scope set at 10x, all MOA markings on the
reticle are correctly displayed as 10, 20, 30, 40, and 50 MOA.
• If you are shooting with the scope set at 5x, the actual drop values will
be 20, 40, 60, 80, and 100 MOA.
• If you are shooting with the scope set at 2.5x, the actual drop values
will be 40, 80, 120, 160, and 200 MOA.
Example
Your drop chart indicates you need a 20 MOA holdover to make your shot.
With the scope set at 5x, you should hold on the 10 MOA reticle mark
which yields the actual 20 MOA that you need.
Example Using a 360 fps Crossbow at a 40-Yard Distance
Shooting with the initial adjustment as suggested in the sample drop chart
should allow you to hit the target, but you probably won’t hit the bullseye.
1. Dial up 12 MOA on the elevation turret
then aim and shoot at the bullseye using
the reticle crosshair.
2. Measure the distance your arrow hits
above or below the bullseye in inches.
3. Divide your measurements by .4 to calculate value in MOAs (.4 comes
from the conversion chart on page 20).
• If arrow strikes low, add your calculated MOA value to 12 MOA.
• If arrow strikes high, subtract your calculated MOA value from 12 MOA.
4. Shoot again. When you hit the bullseye, record this final MOA
adjustment for future use.
5. Repeat process with targets set at distances of 50, 60, 70, 80 yards, etc.
TIP: Keep your adjusted MOA drop values handy for quick use in the field.
Drop Chart in MOAs
360 fps Adjustments
30 yards 0
40 yards 12 MOA
Drop Chart in MOAs
385 fps Adjustments
30 yards 0
40 yards 11 MOA
50 yards 23 MOA
60 yards 36 MOA
70 yards 49 MOA
80 yards 63 MOA
90 yards 77 MOA
100 yards 92 MOA
Drop Chart in MOAs
425 fps Adjustments
30 yards 0
40 yards 7 MOA
50 yards 16 MOA
60 yards 26 MOA
70 yards 37 MOA
80 yards 48 MOA
90 yards 59 MOA
100 yards 71 MOA
Sample
Drop Charts