Thursday, February 17, 2005

Further Mil-Dot

The last post may have had dual signals. This is a subject I am keenly interested in and I did not mean to take a piss at mathematicians.

But nobody really seems to be able to give the low down on the mil-d0t? Are there dueling theories or is it so esoteric that no one even bothers trying to explain it?

This seems to be the best long-range configuration I can come up with, and the mil-dot serves dual purposes: range and compensation.

If you think they absolutely suck, let me know why.

Okay, here goes...

The "mil" part is short for "miliradian", or, one one-thousandth of a radian. A radian is a distance around the circumference of a circle, equal to the radius of that circle. There are 2*pi radians in a circle (since the circumference is equal to 2*pi*radius).

Have I lost you yet? Moving right along...

Now imagine a circle drawn around you, with the radius equal to the range to target. (So you're at the center, and your target is on the circle...) The distance from you to the target is, lets say, 1000 yards. (to make the numbers pretty). Now consider a point one yard left of the target, still on the circle. The angle formed by the lines from you to the target, and from you to the point to the left of the target is one miliradian, or one mil. (well... so close the approximation error is negligable)

So: one Miliradian is approximately (really, really close. If you care, and I haven't confused you too much, I can explain that, too) the angle formed by a right triangle with one leg 1000 units, the other leg 1 unit (and so the hypotenuse equal to sqrt(1000^2 + 1^2)).

Or: one miliradian is 1/1000 of one radian. and pi radians = 180 degrees. (so one miliradian = .180/pi degrees)

The way range estimation works is:

The scope gives you a way to measure the angle between the line from you to the bottom of the target and the line from you to the top of the target, you can calculate the distance out the target is. 1 yard at 1000 yards is one mil. So, if a 36" target is one mil in your scope, then you're 1000 (approximately) yards away. If a 36" target is 2 mils in your scope, then you're (approximately) 500 yards away.

Okay, that explaination is probably only clear to people who already know the math behind it... so I apologize for that. But I hope it's somewhat helpful.

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