How to shoot with a mil-dot reticle in your rifle scope

Rest easy! This is not going to be an extensive discussion on just how and why mil-dots work as a sighting aid. There is only one figure to remember. 

The sighting system was developed by the US military in the late 1970s as an aid for snipers to estimate distance. It is possible, if you know the size of an object, to calculate its range using mathematics. 

So, how tall if that pig you’re aiming at? The fallow deer? The sambar? Fear not — there are other, simpler ways of using the system.

The easiest way to convert the mil dots to a ballistic table is to remember that the distance between mil dots is 10cm at 100m. It’s not quite as simple if you think in imperial measures: 3.6 inches at 100 yards, but the theory is still the same. 

At 200 metres, the dots appear to be 20cm apart; or at 200 yards, the distance between them is 7.2 inches. And so on as distance increases. 

But there is one vital point to remember here. If you are using a reticle in the second focal plane, as most of us do, this scale is only correct at one specific magnification level in a variable-power scope. It will vary scope to scope but you must know what it is and have the scope set to it. The scope maker may provide the info but, if not, you can work it out visually at the range. (First focal plane reticles do not have this issue.)

Knowing this, you then need to know the trajectory of the ammunition you use. You might get this from the packet the ammo came in but that’s not very accurate. If you can measure the muzzle the true muzzle velocity you’re getting, and know the ballistic coefficient of the bullet, there are any number of ballistic programs that will be able to compute the figures you require. 

When you couple the ballistic table with an electronic range finder, suddenly there is a certain amount of confidence relating to hits at long range. 

How far should the ballistic table extend? It depends on the size of the animal and to what extent you want to test yourself. 

To create the chart below, we’ve used the the figures for a .308 Hornady 178gn ELD-X, which has a BC of .552 and was measured doing 796.7m/s (2614fps) from the muzzle of a CZ 600 Range. Coupled with a 200m zero range, we fed the info into Hornady’s online ballistic calculator, which produced this:

Provided you accurately sight in the rifle with the projectile impact 6.5cm above point of aim at 100m, the figures will be correct.

The columns that matter to us out in the field are the range and the come-up in mils; your mil-dot reticle, set on the correct magnification, will match this perfectly.  

As an example of practical use, if the electronic rangefinder indicates that the proposed target is 350m away, you need to raise your aim 1.4 mils to allow for the fact the projectile will hit 50.4cm below line of sight. 

The system is simple and works.

But, be warned, there are sights that claim to be fitted with mil-dot reticles that are wrong. 

Some years ago, I came across a deal on the web for a 6×24 sight at a ridiculous price. For less than $100 Australian, it arrived in the mail from overseas. To be honest, I bought it as a joke. 

It had a mil-dot type reticle, but the actual distance between the dots at 100m was only 5.5cm, not the normal 10cm of a true mil-dot. I had to create a unique table in order to use it properly.

A recent purchase of yet another Chinese-made sight also advertised a mil-dot reticle, but again, the true value was only 5.5cm. You have been warned.