Vortex Optics VIPER PST 6-24X50 RIFLESCOPE - Manual (Page 7)

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RIFLESCO PE
When using the reticle for elevation correction rather than dialing, the
MOA marks on the center horizontal crosshair can still be used to help
visually reference windage corrections. Remember to hold the reticle
into the wind.
Basic windage correction using drop line on reticle
When estimating moving target leads, the MOA marks on the center
horizontal crosshair can be used. Estimating moving target leads will
require knowing yardage distance, wind speed, moving target speed, and
total bullet flight time (including rifle lock time). Bullet flight times can be
roughly calculated based on fps velocities or a ballistic calculator.
Basic moving lead correction
9.4 MOA reticle correction for a target moving 3 mph at a distance of 800 yards.
No wind. Total bullet time of flight from trigger pull is 1.5 seconds during which
target travels 6.6 feet. Elevation already dialed into turret.
20 mph wind
Full value wind at 90 degrees
8 MOA reticle windage correction at 500 yards in 20 mph crosswind using
10 MOA reticle drop line.
Note: Correctly estimating moving leads is very difficult and requires
considerable practice and knowledge beyond the scope of this manual.
Example
Direction of Movement
Example