Scope Range Finder

If you have a scope with sub-tension markings on the reticle, this utility will compute the ranges which correspond to the BDC (Bullet Drop Compensation) markings for a particular size target.To compute the ranges you will need to have the MOA or MIL data which correspond to the markings. Some manufacturer’s provide this information on-line or you can send a message to customer support requesting them.

Note that the MOA/MIL data is magnification specific. You may only be provided with the MOA/MIL values for the minimum and maximum magnification settings. If you wish the values at an intermediate magnification setting, they can be determined by taking the smallest magnification value and dividing it by the multiplier needed to get the value at the desired magnification. An example is below:

You have a 3×12 scope with a MOA value of 8.00 for the 3x BDC1 setting. The MOA value for the 6x BDC1 setting is (8.00 / 2) = 4.00 MOA since 6x / 3x is 2. The MOA value for the 9x BDC1 setting is (8.00 / 3) = 2.667 MOA since 9x / 3x is 3. To verify, check that the computed value for the 12x BDC1 setting (8.00 / 4) matches the value provided by the scope maker.

The most useful values will normally be those for the highest scope magnification, since you will usually use the highest scope setting for long range shots.

The Using BDC Scope as Range Finder utility is accessed from the Shooting Utility screen.

On the Scope Range Finder view:

  • Set the distance units as you require in Select Input Units (Yards, Feet, or Meters).

  • Set the Scope BDC Units (MOA or MIL)

  • Type in the Scope Description and Scope Magnification information if you wish to save the computation results.

  • Enter the Scope BDCn data provided by the scope maker in the Scope BDC Units selected above.

  • Change the Target size column to meet your needs.

For North American hunting purposes some commonly used animal chest sizes from brisket to top of the back are:

  • Pronghorn antelope ~ 15″

  • Small Deer (Texas, Arizona) ~ 14″

  • Large Whitetail and Mule Deer Bucks ~ 18″

  • Desert Ram ~ 18”

  • Dall Ram ~ 22”

  • Stone and bighorn Rams ~ 24″

  • Mountain Goat Billy ~ 24″

  • Cow and Spike Bull Elk ~ 24”

  • big Bull Elk ~ 30″

  • big Bull Moose = 40″

Source: Jack O’Connor’s book The Hunting Rifle

Select the Compute button to compute the range of the specified target size for the BDCn sub-tension markings.

Select the Save button to write the computed data to a csv file in the 1-Shot folder of the Downloads directory. The file name is taken from the Scope Description, Scope Power and _Ranges. The data in the file is separated by commas (“,”).

Select the Done button to exit the view.

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