Vortex Optics CROSSFIRE 4-16X50 AO - MIL DOT ILLUMINATED User Manual

Reticle Manual
Mil Dot
Vortex Mil Dot Reticle
The Vortex Mil Dot reticle is an extremely versatile reticle allowing the user to do range estimations, holdover and wind drift compensation, as well as moving target leads.
Vortex M il Dot Reticl e
When used with second focal plane riflescopes it is very important to understand that in order to use the listed subtensions correctly, the scope must be set to a particular magnification (usually the highest). Consult the riflescope owner’s manual for the correct magnification to be used. Of course, the standard center crosshair can always be used at any magnification.
The mil dot reticle subtensions are based on the milliradian (mrad for short). 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. These angles and arc scales are used to estimate range and bullet trajectory drop with the mil dot reticle. There are 6.283 radians in a circle and 1000 milliradians in a radian for a total of 6283 milliradians (mrads) in a circle.
1 Mil Widt h at Distanc es
100 yards ------------------------ 3.6 inches 200 yards ------------------------ 7.2 inches 300 yards ----------------------- 10.8 inches 400 yards ----------------------- 14.4 inches 500 yards ----------------------- 18.0 inches 600 yards ----------------------- 21.6 inches 700 yards ----------------------- 25.2 inches 800 yards ----------------------- 28.8 inches
An mrad will subtend
3.6 inches at a distance of 100 yards. Most riflescopes with mrad adjustments use .1 mrad clicks which subtend .36 inches at 100 yards.
Vortex M il Dot reticl e subtensions shown in milliradians (mrad or mils).
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Ranging
Windage Compensation
To use a mil dot reticle for ranging purposes, you must have an object of known dimension at the same distance as your target to which you can compare the mil spacing. Then you can use the simple formula below to calculate distance. This easy formula can be used for all ranging situations:
Known Di mension (in yar ds) x 1000
Mils Read
Examples of Objects of Known Dimensions
= Yards to Targ et
• A fence post known to be 36 inches tall that is next to the coyote you’re shooting at.
• The brisket-to-back distance of 18 inches on a whitetail buck.
• The height of 10 inches for a standing ground hog.
• A target that is 20 inches in diameter.
Using the first example, place the reticle on the fence post with the horizontal crosshair even with the ground—remember that the scope must be turned to the correct magnification. Reading the mils, the fence post equals 2 mils in height.
Using the mil dot reticle for windage and moving target leads will require thorough knowledge of your cartridges ballistic performance and experience in properly reading wind strengths. Again, the scope must be at the correct magnification for this to work.
Remembering that 1 mil equals 3.6 inches at 100 yards, 7.2 inches at 200 yards, 10.8 inches at 300 yards, etc., use the mil dots on the horizontal crosshair to hold-off the required distance. Remember to hold into the wind direction when doing this.
Example of Wind Drift Compensation
Lets say you’re shooting at a target 400 yards away with a small crosswind. Through experience, or after consulting ballistics information, you believe the bullet will wind-drift about 7 inches. At 400 yards, each mil spans 14.4 inches (see chart on page 2), so you’ll need to hold about ½ mil into the wind to correctly compensate and make your shot.
Using the formula shown above, you can calculate the distance to the fence post (and the coyote) at 500 yards.
1 Yard (36 in ches) x 1000
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500 Ya rds
=
2
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Holdover
Once a target has been ranged, the mil dot reticle can be used to quickly estimate proper hold-over on longer shots. In order to do this, you will have to be very familiar with the ballistics of your particular weapon and ammunition at all distances. It can be very helpful to keep a printed ballistic chart handy. As always, your scope must be set to the correct magnification.
Example of Reticle Holdover
Let’s say you’ve ranged a deer with your mil dot and determined that he is 300 yards away. You’ve zeroed in your rifle at 100 yards, and know through practice and ballistics info that your bullet will drop 11 inches at 300 yards. You know that the mil spacing on the reticle is equal to 3.6 inches at 100 yards. This means the mil spacing will be 10.8 inches at 300 yards. Therefore, to make your shot you’ll need to hold the center crosshair about 1 mil high from the deer’s vital zone.
For additional information on using the mil dot reticle, be sure to consult the Vortex Long Range Ballistic Compensation (LRBC) program. You’ll find this at www.vortexoptics.com.
The LRBC program will allow users to input their specific ballistic information and, then, see a graphic representation of the mil dot reticle displaying specific yardages and wind drifts for each dot.
If you have any questions, contact Vortex Optics. Call us at 800-426-0048 or e-mail service@vortexoptics.com.
Vor tex Optics 2120 West Greenview Drive Middleton, Wisconsin 53562 USA
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MIL-DOT-11A
© Vortex O ptics USA
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