The reticle of telescopic sights is the sight's aiming reference. The most widely used and well-known is the Mil-Dot reticle. This reticle allows us to determine the distance to the target we are going to shoot at; to do this, it is simply necessary to know the size of the target. This distance is what we need to adjust our scope.
Mil-Dot Reticle
The measurement system of the Mil-Dot reticle is based on trigonometric calculations, with the unit of measurement being the milliradian (mil), which is 1/6400th of a circle. Although this might not seem to mean much, the important part is that one mil in a scope represents observing one meter at one kilometer. In other words, the distance between two dots on the reticle is as if we were looking at an object measuring one meter at a distance of one kilometer.
Another important concept is the MOA. One MOA is 3 centimeters at 100 meters (2.98 centimeters in reality), 6 cm at 200 meters, 9 cm at 300 meters, etc. This begins to give us an idea of how a Mil-Dot reticle works. The angle does not change; what changes is the perception of the object at a distance.
You can learn more about MOA by visiting another article on our blog: What is MOA?
Formula to calculate the distance to the target
Taking into account these two important concepts—MOA and the reticle—we can begin to calculate the distance of an object. To do this, we only need to know the measurement of the object and look through the lens to see how many mils our target measures within the reticle. Once we have these data, we apply the following formula:
The Mil-Dot reticle is used to determine the shooting angle at which we should shoot. This is possible thanks to the Milliradians, the unit of angular measurement used in this type of professional reticle through the use of thousandths. On Mil Dot reticles the markings appear in Miliradians or thousandths, 1 Miliradian (1 mil) equals 10 cm or 3.6 inches at a distance of 100 metres or 100 yards.
For example if you wanted to aim at a target that is an unknown distance away accurately, all you would need to know is the total size of the target and the number of dots your Mil Dot reticle shows you that the target measures. In the image below, you will see a target that measures three dots according to the scope, to measure an object you have to put the bottom of the target in line with the centre crosshairs of the scope and count the number of dots it measures to the top of the object.
So to calculate the distance to a diameter of 17 cm, which appears from a .size of 3 mils in our Mil Dot viewfinder, as shown in the picture above, these clusters would have to be made. Keep in mind that the measurement of the object is done in metres, so the 0.17 m. of target multiplied by 1000 and divided by the size of Miliradians, in this case 3 mils.
( 0.17 X 1000 / 3 )= 56.6 metres
In this case,you will be 56 metres from the bullseye.
If we would like to know the distance to a target, but we do not know its total size, we can always approximate the measurement and use the same formula, with the understanding that the calculations will give us an approximate distance.
Adjusting the viewfinder once the distance is known
The technically correct thing to do, once the distance is known, is to make the appropriate "click" adjustments on the scope according to the MOA clicks on the turret to correct the reticle to the shooting distance according to your calibre of ammunition.
The great thing about the Mil Dot reticle is that in addition to its telemetric use it has a very practical application, and that is that you can use the reticle dots as references for aiming at different distances and objects of different sizes.
What do you think of Mil Dot reticles? Maybe after learning a little more about them you will decide to buy one, don't forget to comment on your experience.
