Rangefinding Made Simple
What is a mil?
1 mil of angle covers one yard at 1000 yards. 3.6" at 100 yards. Or 1 meter at 1000 meters. Some scopes have a reticle graduated in mils. The number of inches covered by the mildot is a measure
Lucky metric users know that 1 mil of angle covers 1m at 1000m. 10cm at 100m. Or 4" at 100m, 12" at 300m. I learned to shoot in the Army on metric ranges, so I estimate range in meters anyway.
One mil on your reticle covers 5/6 of a 12" target at 8x magnification. What is the range? How many scope clicks?
I made up the "MilRange" system to avoid mental arithmetic.
MilRange is the number of inches on the target covered by one Mildot.
Print the MilRange table for the load you are using, tape it to your rifle, that's all you need. No slide rule, calculator or ability to remember anything is needed. The table has sight
adjustments depending on how many inches your mildot covers on the target. Simple as that.
You say 'My mildot covers about 10" of that 12" target, MilRange equals 10.
Read off the scope adjustments or MOA holdoff for drop and wind, and you are adjusted. The range is around 350yards at 8x magnification, but you don't need to think about it.
The table gives you drop and windage in both 1/4 MOA scope clicks and inches. You can have Mils instead of scope clicks if you prefer.
Or "My mildot covers that 12" target plus another 6",
MilRange equals 18".
Look up the table for sight adjustment. The range on 16x magnification is 280 yards, but you just look at the sight adjustment.
Here's the table for the second example. See if you can do it by yourself.
The example is .308 Winchester, 175gr, 2740 fps, BC 0.46, 100m zero, 10mph crosswind at 90 degrees. But you can print a table for any load you like.
You can select a table in either 1/4MOA clicks, or mils. So you can either use scope adjustment or hold off x mils.
Don't use a scoped rifle to estimate range on anything you are not prepared to shoot.
A minute of angle is a one inch at 95.55 yards, or 1.05" at 100 yards (see below for the exact value).
Most people say "one inch at 100 yards" for the sake of simplicity.
Scope sights usually have adjustment in 1/4 MOA clicks, so if your zero is off by 1" at 100 yards, that would be 4 clicks to adjust. Off by 1" at 50 yards, 8 clicks.
If the scope has 1/2 MOA clicks, off by 1" at 100 yards would be 2 clicks to adjust.
That's all there is to it. Some scopes allow you to set your zero, and then adjust the scope knobs for elevation and windage, You get elevation and windage from a ballistics table.
If the drop is 2" at the target's range, you can aim 2" high instead of adjusting the scope. You can memorize the bullet drop at 100, 200, and 300 yards for your rifle and ammuntion, so you
can make the necessary adjustment.
It's worth knowing the amount of windage for a 10 mph wind at these ranges too. 10mph means loose papers blowing around and small branches moving. It also means at right angles to the firer.
If the wind is at an angle, you guesstimate what proportion of the wind is at right angles to the direction of fire.
The wind accelerates the bullet in the wind direction. So doubling distance more than doubles wind deflection.
This makes is long-range shooting difficult, you may have to get closer to the target if it is windy.
Take a scientific calculator. Type in 1, TAN, multiply, 60, equals. The answer is 1.04730389569305514590773371318367, which is the number of inches covered (or subtended) by a minute
of angle (MOA) at 100 yards.
Mil-Ranging on non-Mildot Scopes
You can use a non-Mildot scope to estimate range using this program. Say your fixed 4x scope crosshairs cover 0.4" at 25 yards. Run the program with different scope magnification numbers (5.6x in
this case) until the MilRange at 25 yards is 0.4" (or 4" at 250 yards).
So now you print the table, and you can use it to estimate range, pretending the crosshair width is a Mildot.
If your scope is adjustable, you have to use the same magnification for when you estimate what your crosshairs cover, and when you estimate range with your printed table. Otherwise it doesn't
Don't use a scoped rifle to estimate range on anything you are not prepared to shoot. You can carry a $25 compact scope in you pocket and use that for ranging in the field.
Free Ballistic Simulator Software updated Sunday August 01 2010 at 11:43am. Email Frank Clarke About Frank Clarke