range-estimation-featured

Range Estimation

In Blog by Rich3 Comments

Today we’re going to discuss the practice of range estimation. This is another one of those things that for some reason people seem to consider it a critical skill that is utilized on a regular basis. I think the modern day range finder has become the better mousetrap. When I was reading and learning about range estimation the people discussing the topic took the position that it is slow, imprecise, and only used in what would be considered emergency circumstances. I can tell you that after several years learning, shooting, and competing in the tactical rifle world that assessment is correct. I do think we should all know how to do it as a backup method. After all, batteries die, and electronics can fail you at the worst possible moment. However, I don’t think the practice of range estimation is something you need to be overly concerned about. So don’t lose sleep over this one, okay?

What is Range Estimation?

This is the process of using one of a few methods to make an educated guess as to the distance between two points. The most common involves using magnified optics of a rifle or spotting scope, and a reticle with specific subtensions, to view and measure the size of an object at distance. Then, with the help of a little math, you can make an educated guess as to the range of the object based on the math and size of the object measured by the reticle. It can also be done with maps, gps, or the most precise of the methods, the laser rangefinder. The process of using a reticle to “MIL” a target has its roots in the Military world, like a lot of long range shooting practices. The key point here is to keep the time period this all came about in mind when discussing the process of range estimation. Range estimation came about as Military shooters wanted to engage distant targets but they didn’t have the tools we have today. Back before laser range finders were commonplace and portable a shooter had to come up with a way to carry out range estimation. There are several ways to do it.

Range Estimation: Milling

The most common method of range estimation people talk about is milling a target. This is done by using the reticle of a scope calibrated in milliradian (MIL) measurements. Though it can be done with an MOA reticle as well. The scopes used when this came about had something call Mildots on the reticle, thus the term “Milling”. Modern scopes are still calibrated in MILs but you see less of the mildot designs and more using the hashmark design. I tend to think the MIL hash reticles are more precise but as long as the distances between dots, hashes, or whatever graduation the reticle uses, are correctly spaced the technique will work the same way.

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This is a Nightforce mildot reticle, the distance between the center of the dots is 1 Mil, so two dots out from center is 2 Mils, so on and so forth

The process of Milling a target is as follows. You use the Mil based reticle of the scope to measure the height of an object. Say for example a stop sign at distance. Say for this example that the stop sign appears to be two Mils high in the scope. Now comes the math and some knowledge. This only works if you have an average or known height to compare the Mil size to. A stop sign is about 36 inches high. Now comes the math formula to combine the information. To range a target in yards with Mils you will take Height of Target in InchesĀ multiplied by 27.78. That number, in our example 36 x 27.78 = 1000.08, is then divided by the Height of Target in Mils which gives us the range to target. In our example, the range is 500.04yds to the stop sign.

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As an example, this stop sign measures about 2 Mils high in the scope

Again, this is not something you can do all that quickly. Unless you happen to be just awesome at that kind of mental math, you probably need a calculator to do this. You can speed the process up by rounding some numbers off and using 30 instead of 27.78 but using shortcuts like that make the Milling process of range estimation even less accurate than it already is. This is why its used as a backup and only in a situation where a rangefinder isn’t available or there isn’t time to use it. An example might be a relatively close shot while hunting but the animal is about to be obscured and is only exposed for a few fleeting moments. You can quickly MIL the shoulders and use an average height of the animal to get a quick and dirty range for the target.

Map Range Estimation

Another technique for range estimation is by using a map. I’m not going to go into the math here because maps come in different grid systems and on different scales. However, it should be fairly easy to understand that if you have a map that includes your location, and the location of your target, you can perform some range estimation to find the distance to your target. You have to reference the scale of the map and use that to measure the distance between your position and the target. Obviously approximating those positions will introduce error. The larger the scale, the less precise the range estimation you are able to perform.

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Example of a UTM map of part of a Denver suburb, there is a scale at the bottom, and the map is divided into a precisely sectioned grid

This is another Military technique. Most civilians, hunters, and even Law Enforcement don’t carry highly accurate grid coordinate maps of the area they happen to be operating in. So you will see this more in military circles since those guys often have to navigate by map and are often operating in unfamiliar territory. Having access to accurate maps makes all the difference. If you are interested in using maps, look for maps of your shooting area from the US Geological Survey that are divided into UTM Grids. You can purchase map rulers that make measuring the distance between points fairly easy.

GPS Range Estimation

If you have access to GPS coordinates you can use online tools, apps, or handheld phone and computer devices to calculate the distance between two sets of coordinates. This is essentially a more accurate form of map range estimation. It’s the same idea and process only instead of guesstimating the firing position and position of the target on a map you have actually checked both with a GPS receiver, and recorded the coordinates. You also don’t necessarily need a map for this technique. If you write down the coordinates where you plan to shoot from, and then the coordinates of where you hang up your target, you can find the distance between them. The math is kind of complex, honestly I suggest using an app or laptop or some kind of gadget to do the math for you.

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Using a Trimble Nomad to pull in the precise GPS location of the device, this can be utilized in conjunction with a map, and a rangefinder, to determine the distance between two objects

Laser Range Estimation

This is by far the most accurate way to perform range estimation. Why am I still calling it range estimation if it’s such an accurate method? The reason is this, even with a laser, there is error introduced into the process. If you miss the target with the laser and it hits something else, you will still get a result. Is it the one you really want, though? This is more common than you might think. If you are freehanding with a laser ask yourself how steady the reticle of the laser is on the target. What else does it cross over between the time you push the button and the time the answer is displayed? Did you range the target? Or the hill behind it? So how do you make the use of a laser for range estimation as accurate as possible?

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Vectronix Terrapin laser rangefinder is an almost perfect way to determine the distance between two points

For starters, buy the absolute best laser rangefinder you can afford. In the context of precision rifle shooting the distance to the target is incredibly important! If that number is incorrect your odds of a miss multiply exponentially. I was lucky enough to snag a Terrapin before Vectronix discontinued production of the Terrapin. It’s an absolutely awesome rangefinder. The price is also pretty amazing. Amazingly high. You do get what you pay for though so if you are in the market for a high end range finder for range estimation, Vectronix products are top shelf. Other products I’ve heard good things about and messed with in passing are the Swarovski EL Range finder binos. Those are pricey too. The Leica 1600B has a good reputation and is considerably more affordable. The next step down and probably the best bang for buck are the Bushnell Elite series. Either the 1600 models or the newer Bushnell 1 Mile monocular or binocular models give you a lot of performance for the price.

Think of using a laser range finder like you shoot your rifle. Try to build a stable position if you are trying to range a distant target. If your range finder will reliably range targets to 2000 yards, that doesn’t mean you can freehand hold the range finder on target long enough for a return. Try mounting the range finder on a tripod. Or steady it with your bag. The same things that work for steadying your rifle for a shot work for steadying your range finder!

Wrapping Up

We talked about a couple different forms of range estimation. I spent the most time on Milling because that’s what most people seem to be curious about. The math is also a lot simpler to explain, for the most part. However, this is not the most accurate thing to be doing. In reality, the most accurate form of range estimation is a laser rangefinder. That will tell you, in no uncertain terms, the distance between the shooter, and the target. Be aware of upward and downward angles as that will have an effect on the adjustment needed to hit the target. A rangefinder is your best bet so try to get the best one you can afford. If you plan to use a map, make sure you have actual USGS UTM maps that have precisely calibrated grids. A GPS receiver and a cell phone app are probably the next easiest bet behind a rangefinder. As a last resort, you can MIL the target for range estimation. If you have questions or a comment, drop it in the comments below!

Owner and Proprietor of AccuracyTech, LLC. Rich is a Firearms Enthusiast, Precision Rifle Competitor, and Writer. He is committed to bringing readers quality reviews and articles related to the Precision Shooting Sports. If you have any questions for him, please use the contact form on the site.

Comments

  1. You say the mil dots are 1 mil apart but don’t think that is entirely correct. They are usually 0.8 mils apart and 1 mil center to center.

    It may just be semantics but it’s important to have the measurement correct.

  2. I mil with a Votex spotting scope and then, knowing the size of the target, use a small round slide rule (fits in a shirt pocket) to calculate the range in either meters or yards. The method is very quick. It takes me longer to put on my glasses than it does to calculate the range.

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