Range Estimation and Windage with Mil Reticles – Part 1, by N.E.

“Tossing a bit of dry grass in the air as he had done at countless high-power matches, T.K. judged the wind. He complained, ‘Darn, I wish I had a windage table for .50 Browning. I’ll just have to guesstimate.’ Getting ready for his first shot seemed to take forever. First, he made several adjustments to the bipod. Then he squirmed around trying to get into a comfortable prone position. He tried placing his cheek on the stock several times before he found a position that was both comfortable and provided a full field of view through the rifle’s ten-power Leupold scope. Next, he concentrated on getting himself relaxed and controlling his breathing. Then, and only then, did he pick his primary and secondary targets.

‘I’ll spot for you,’ Dan said, as he pulled out his binoculars. Dan lay propped up on his elbows, peering through the rubber-armored seven-by-fifty Steiner binoculars. ‘What do you make their range, about eight hundred?,’ Fong asked.

‘More like nine-fifty,’ T.K. remarked coolly.” (Patriots, p. 229).

If reading the novel Patriots doesn’t get you pumped up, maybe you’re on the wrong web site. In this article, I provide a “how-to” on long-range shooting by showing you how to range targets using a mil-based reticle and ways to read the wind.

Long-range shooting works well with prepping because being true to the meaning of the word, you need to prepare in advance so that your end result meets your expectations. Shooting at longer ranges requires an advanced understanding of several things, but, I assure you, it is not hard once you get into it.

Shooting at longer distances does require practice and patience, however. Long range is also not for everyone due to several factors such as firearms interest, cost, and range availability. Or, maybe your general location won’t allow you to see beyond 200 yards. However, if you are sitting at your retreat, or at your home and you can see further than 200 yards, then learning how to use a mil based reticle can help you in the most basic sense of just calculating distance.

The technique of ranging distance can also help to better assess your environment, too. There are spotting scopes and monoculars on the market that come with a mil-based ranging system etched into the glass. So, this technique can work for simply observing through an optic that is not attached to a firearm.

Scopes are a very important part of this equation and they come in all sorts of shapes, sizes, features and prices. I am of the opinion that the most important part of selecting a scope for long range is to make sure that the reticle and turrets match.

This is to say that if you are working with mils, then both your reticle and turrets should also be in mils. When I first became interested in long-range shooting, the most widely available scopes had mil-dot reticles with MOA turrets. Those scopes required an equation to convert the different units of measure and that conversion was another step that made everything more complex than it needed to be. As mentioned, this article is focused on the mil based system, so for you MOA shooters, that information is for another article.

A main feature of a scope is that they have either a First Focal Plane (FFP) or a Second Focal Plane (SFP) option. Either option is a personal preference. A major difference between FFP and SFP for the end-user is that with a FFP scope, it does not matter which power your optic is set at to measure distance.

With a SFP scope, there is usually a number marked in a different color on the power adjustment ring. It is common for that number to be at 10 or 12 power but it may vary depending on the manufacture and model of your scope. The particular setting that is colored differently on a SFP power adjustment ring is the setting your scope needs to be at in order for your reticle to measure true distance.

The quick way to know if a scope features FFP is that when you adjust the power ring, the reticle will move by either growing in size or shrinking as you move the power adjustment. On a SFP scope, the reticle will always stay the same size when adjusting the power ring.

Understanding the reticle

When breaking down a mil-based reticle, there is the center crosshair with a line traveling up the “Y” axis which connects to circles. These circles represent mil dots and are whole numbered mils. The same is found on the “X” axis. From the center of the crosshair to the center of the first dot, that distance equals 1 mil. The second dot would be 2 mils and so on.

Between the center crosshair and the first mil-dot as seen in Figure 1, that distance is broken down into .1 increments. Being invisible on this particular reticle, these tenth of mil increments are used to measure objects and they correlate to the turret adjustment. In Figure 1, the halfway point between the center crosshair and center of the first mil dot equals .5 mils. The point in which the line just touches the bottom of the first circle, that spot would equal .9. The center of the first mil-dot equals 1.0, or 1 whole mil.

The same unit of measure holds true for the entire reticle. This is to say that the point at which the first mil-dot connects to the line again (top side and opposite of .9), that would be 1.1 mils. The center of the next stadia would be 1.5 and so on.

Figure 1
Measuring Distance

Now that we have a basic understanding on how to use the reticle, how do we use this information to measure distance? To measure distance in yards, you will use this equation.

27.778 X inch size/mils = distance.

Inch size and mils are always going to be variables (they will always be different with different targets), but 27.778 will always be a constant for yards (for meters, the constant is a different number). 27.778 will never change for measuring yards, so when you get out in the field to practice, you may want to memorize 27.778.

When looking at inch size in the equation above, you need to know the size of the object you want to measure. This means that if you are looking over a field or a tree line, you would need to know the size of a particular tree, as an example, in order to range it (almost impossible or takes way too long on the front end prep). However, if you see a coyote, a deer, or even a fence post, you can take the average size of that object to gauge its distance.

In the case of ranging deer, you can measure from chest to tail, or hoof to the top of the back (do not use the head as it is always moving).

As seen in Figure 2, we are measuring a doe from the hoof to top of back (top of front shoulder) using an average height of 36 inches.

Figure 2

From the hoof to the top front shoulder blades, Figure 2 is showing 3.1 mils. Plugging our numbers into the equation we get:

27.778 x 36”/3.1 mils = 322.6 yards.

Does this seem pretty straight forward? Let us try another example as seen in Figure 3.

Figure 3

 

In figure 3, I would measure the doe at 1.9 mils, and plugging our numbers into the equation we get:

27.778 x 36”/1.9 mils = 526.3 yards.

Getting the hang of it?

I have included a third reticle image (Figure 4), so that for those of you interested, you can practice by posting your answers in the comments section.

Figure 4

 

Now that we have learned to range distance using a mil reticle, how does this information help us in making a long-range shot?

Bullet Trajectory

The key here is to know how fast your bullet is traveling. Referred to as Feet Per Second (FPS), you can collect the data for your FPS by using a chronograph (chrony). Most factory ammo has an FPS listed on the box, but I have never seen that number actually be true. There are several reasons for this, but that is beyond the focus of this article (barrel length, powder charge, type of power, bullet weight, distance between muzzle and chrony, and or temperature). However, using the factory FPS can work in a generalized sense, but the further out you go, the less accurate generalized information becomes.

To calculate FPS, shoot 10 rounds through the chrony and then take the average of those 10 rounds. The outdoor temperature when you chrony can also affect your FPS. For instance, if you chrony on a 80 degree day but later use that data during the winter, the atmospheric conditions have changed and the air becomes thicker in colder weather. This in turn slows down your bullet. On hot days, the air is thinner, thus allowing your bullet to travel faster. The differences in temperature (and altitude) can determine if you are high, low, or miss your target entirely. Really just depends on how far out you are going. Being mindful of these atmospheric changes, you may benefit by collecting chrony data for 20, 50 and 80 degree weather.

Once you have your FPS, there are all sorts of programs and ballistic apps on the market that will allow you to plug-in your FPS. These programs will give you your flight trajectory (drop) as well as tell you how many “clicks” you need to adjust your scope for a particular distance (more on clicks below).

I personally do not use a phone app, but I see many people do. I use a ballistics program on my computer which allows me to enter my FPS, atmospheric conditions and the bullet I use in order to generate a range card. I divide my range card into 50-yard increments out to the distances I would intend to shoot for a particular caliber (0 to 1000 yards in a good place to start). I then print that range card, use a poor-man’s laminate (clear packing tape), and either tape that card to the rifle stock, place a duplicate in an admin pouch, or use a referee-style wristband with a card slot to store the range card.

Turrets

Ballistic apps and data cards will calculate your drop and this could be thought of as “clicks” in adjustment of your turrets in relation to a particular distance. At the beginning of this article I talked about being sure to have your reticle and turrets match. Then having explained how to use your reticle, that reticle translates to your elevation and windage turrets.

One “click” on your turret equates to .1 mil of adjustment on the reticle. Turning both clockwise and counter-clockwise for the elevation, the turret will adjust your point of impact (POI) or point of aim (POA). The same holds true for your windage adjustment (left and right). As can be seen in Figure 5, these tenth-of-mil increments are marked on the turret, with the number “1” equaling 1 mil or 10 clicks.

Figure 5

 

Returning to Figure 2 in which we ranged that deer at 322 yards, we would then look for that distance on the data-card to find 300 and 350 yards. In an example, let us say our data shows 1.3 clicks for 300 yards and 1.7 clicks for 350 yards. As our target is at 322 yards, try splitting the difference with perhaps a 1.5 value for elevation adjustment. 1.5 mils are equal 15 clicks on the elevation turret. Make sense? If not, please let me know in the comments section and I will try to answer your question the best that I can.

(To be concluded tomorrow, in Part 2.)

Original Source