What is a Mil Dot Scope?

[Mo]

Original Article

What is a Mil Dot Scope?

To answer that, we first have to know what a mil is.

A mil dot reticle does not refer to the military. The MIL in mil dot is a shortening of the term milliradian. You are familiar with degrees as measurements of angle. You also know from high school geometry that there are 360 degrees in a circle. As the circle grows larger in circumference, the number of degrees does not change, but the distance between each degree along the circle does increase. You may also know that degrees are divided into smaller units called minutes. There are seconds, too, but they are too small for this discussion. A degree is divided into 60 minutes. At 100 yards distance, the angle of one minute is approximately one inch. So if the centers of the two bullets farthest apart in a 100-yard group are about one inch apart, we call that a minute-of-angle group. Get it? At 200 yards, a group measuring two inches center- to-center equals a one minute-of-angle group. At 400 yards, it's a four-inch group. At 50 yards, it's a half-inch group.

Now what is a mil?
One mil of angle is approximately 3.6 inches long at 100 yards, and that is close enough to 3.5 minutes of angle to be convenient. In Leapers mil dot scopes, the centers of the dots are one mil apart. If the scope is variable power, this only holds true for the highest power setting.

So, if your bullseye is 3.5 inches in diameter and 100 yards away, it will touch the centers of any two dots next to each other. If it appears only half that size through the scope (from the center of one dot to half the distance to the next center) your target must be about 200 yards away. If the same bullseye spans the distance between the centers of three dots (two with an extra dot between them), your target is about 50 yards away.

Sniper rifles have mil dots on both horizontal and vertical crosshairs so they can measure height as well as width through their scopes. A six-foot tall man is also 72 inches tall. At 100 yards, he would appear to be just over 20 mils tall. At 1000 yards, he would be close to 2 mils tall.

Military binoculars and gunsights are usually equipped with mil reticles. On the standard crosshairs are other short lines that mark mill angles. These are often referred to as rangefinding reticles. To use them that way, you have to know how to apply the correct mathematical formula, plus you have to know the approximate size of your target.

What else can you use the mil dot reticle for? Well, if you are shooting in a crosswind, you can use the dots as additional aim points to compensate for wind drift. If you notice the strike of your pellets in relation to the dots, you can aim off to one side by placing a dot along the horizontal reticle over the target instead of the crosshairs. By choosing the correct dot, you can easily adjust for how much the pellet will drift in the wind and end up with a perfect shot every time. Better still, there is no math involved!

>There are several other articles that explain how a MilDot reticle works, but this seems simple enough to understand<

[ai]

Another point- The first part of the article above explains about Degrees being divided into 'Minutes' (of angle) (MOA). The Elevation and Windage knobs also work by making adjustments in 'minutes' (usually a turn of one large unit, divided into four clicks, equals 1" at 100 yards). So if one is looking for a scope that is easier to use for rangefinding and adjustments through the W&E knobs or holding over/under, a MOA scale reticle is also available from some scope manufacturers.

As for Mil Dot reticles, they work well with airguns. After zeroing with the center of the reticle at 10 yards/meters, one can determine through trail and error the range at which the dots on the vertical apply to different ranges. Then, those dots will remain true for their respective range REGARDLESS of the magnification.

[diskaon]

since we are in the knowledge sharing mode, i will not be off topic if I ask about the sights in abhinav bhindras air rifle.

there is a rear sight and a front sight both optical, but unlilke the normal scope that Ihave seen. what is that kind of scope called.?

[ai]

Firstly a correction in my post above- usually four clicks equal one inch at 100 yards. Some scopes have a finer adjustment- Bushnell Trophy 6-18 has 8 clicks in one unit that makes a change of 1" at 100 yards.

The question would be OT, as competition 10M or any other Olympic discipline does not have any sights that magnify the target or use glass. They are simply 'peep' sights. The rear one is a very finely adjustable micrometer.

You will find details through an internet search. I have just taken to competition, and my knowledge about competition equipment is bleak!

[dev]

Original Article

What is a Mil Dot Scope?

To answer that, we first have to know what a mil is.

A mil dot reticle does not refer to the military. The MIL in mil dot is a shortening of the term milliradian. You are familiar with degrees as measurements of angle. You also know from high school geometry that there are 360 degrees in a circle. As the circle grows larger in circumference, the number of degrees does not change, but the distance between each degree along the circle does increase. You may also know that degrees are divided into smaller units called minutes. There are seconds, too, but they are too small for this discussion. A degree is divided into 60 minutes. At 100 yards distance, the angle of one minute is approximately one inch. So if the centers of the two bullets farthest apart in a 100-yard group are about one inch apart, we call that a minute-of-angle group. Get it? At 200 yards, a group measuring two inches center- to-center equals a one minute-of-angle group. At 400 yards, it's a four-inch group. At 50 yards, it's a half-inch group.

Now what is a mil?
One mil of angle is approximately 3.6 inches long at 100 yards, and that is close enough to 3.5 minutes of angle to be convenient. In Leapers mil dot scopes, the centers of the dots are one mil apart. If the scope is variable power, this only holds true for the highest power setting.

So, if your bullseye is 3.5 inches in diameter and 100 yards away, it will touch the centers of any two dots next to each other. If it appears only half that size through the scope (from the center of one dot to half the distance to the next center) your target must be about 200 yards away. If the same bullseye spans the distance between the centers of three dots (two with an extra dot between them), your target is about 50 yards away.

Sniper rifles have mil dots on both horizontal and vertical crosshairs so they can measure height as well as width through their scopes. A six-foot tall man is also 72 inches tall. At 100 yards, he would appear to be just over 20 mils tall. At 1000 yards, he would be close to 2 mils tall.

Military binoculars and gunsights are usually equipped with mil reticles. On the standard crosshairs are other short lines that mark mill angles. These are often referred to as rangefinding reticles. To use them that way, you have to know how to apply the correct mathematical formula, plus you have to know the approximate size of your target.

What else can you use the mil dot reticle for? Well, if you are shooting in a crosswind, you can use the dots as additional aim points to compensate for wind drift. If you notice the strike of your pellets in relation to the dots, you can aim off to one side by placing a dot along the horizontal reticle over the target instead of the crosshairs. By choosing the correct dot, you can easily adjust for how much the pellet will drift in the wind and end up with a perfect shot every time. Better still, there is no math involved!

>There are several other articles that explain how a MilDot reticle works, but this seems simple enough to understand<

Thanks Moa i now understand the range finding bit with the mil dot. Course mine is on an air rifle so I won't be shooting that far...but really nice write up.

Dev

[Mo]

Hi Dev,

Your welcome, but I did not write it. The original article link is included at the top.

But I'm glad you found it helpful.

Mo.

[TenX]

Firstly a correction in my post above- usually four ...as competition 10M or any other Olympic discipline does not have any sights that magnify the target or use glass....

Right there AI
No magnification is allowed and only plastic is allowed in the fore sight. Although, the rear sight will have some optics that can only give a tint, have finer adjustment and have polarization filters.