Alternative Methods of Range Estimation

Introduction

Well, first off, there is not a set number of other forms of range estimation, I plan to just cover some common ones, and some others that I, and others, have discovered over the years that may be somewhat unique. Some of them involve using certain reticules, and others may involve pushing a button. But that being said, there are several good alternatives when mil-dots are not an option.

Laser Range Finder (LRF)

Come on now, lets all be honest, there is NO better way to estimating range than using a Laser Range Finder. At the push of a button you will have range accurately estimated to within just a yard/meter or two. Surely, this is the end all! Well…. perhaps, but that doesn’t mean it has no limitations.

Leuica 1200 LRF

First, excepting the military and their MELIOS LRF that is good to 10,000 meters (it was designed for artillery use) all LRF’s have a limited power of laser. Most commercial units now go from 400 – 1500 yard power on the top end. Those 1500 units sound just about perfect, don’t they? Well, do not get caught up in the advertising. They get those 1500y readings on highly reflective (and large) targets. Those same 1500y units in reality will only range to about 800 yards on a non reflective target like a soldier or animal. Weather, air conditions, and other factors can also limit their effectiveness. One thing you can do though to best utilize your LRF, is to range things that are “near” the target that might offer a better signature. Like the side of a building, tree, window, traffic sign, etc. This can be used very effectively when creating your range card in your FFP.

When in your FFP and operating as a team, the spotter should be using the LRF and providing the range. Keep in mind, that most LRF’s provide straight line range, without taking into account slope. The new generation of LRF’s coming out form Leupold, Bushnell and others will actually account for this by using a build in inclometer. If possible a LRF that compensates for incline should be chosen, it makes life nice and easy! Also, when selecting a LRF, I would be sure that it has the standard tripod adapter (threaded hole in the bottom) so that you can more easily keep the unit pointing at that small target at long ranges. I was unable to hold a LRF steady with just my hands to get a reading on a 600m target (20″ x 20″). Some units, like the Leica, have their own tripod adaptors different from the norm. What ever the case, just be sure it can be mounted on a tripod.

In the 1990’s, Swarovski developed an integrated laser range finder in a rifle scope and have been selling it, but the price is very expensive (~$3000) and the laser not the most powerful (1000m on a reflective target). For 2006 Burris optics has released their own integrated LRF Rifle Scope, the laser is still only moderately powered, but the price is much more realistic (~$900), though still not cheap. Both of these units are bulky, and the burris has their ballistic plex reticule, which could make a good combination out to about 500 yards, not the best for sniping, but good for hunting. It is a good concept, though not to maturity yet. What I would LOVE to see is a spotting scope (15-45x or so) with a good strong integrated LRF (at least 1500 on reflective targets). This would be a sniper teams dream.

One thing I have not mentioned in regard to LRF’s, they are electronic, they are semi fragile, so taking murphy’s law into account, you can expect them to run out of batteries or brake just when you need them most. So do NOT become too reliant upon an LRF. Also, certain lasers maybe visible by certain night vision devices, so plan accordingly.

Map/GPS Method

Maps are often overlooked when range estimating, and sometimes they should be, like if the scale is just too large to be useful. But if you are using a 1:25000 or 1:24000 USGA map, you can get “fairly” accurate, at least good enough to give you some aide when estimating with your eyes. A proper protractor is really necessary to do it accurately, but if you have your own position accurately located on the map (this is critical, and a GPS can really help) and with enough experience, one can be fairly accurate at determining the range to a target.

The one EXCELLENT advantage that using a map offers is that you do not have to account for slope dope…. let me say that again (its important)… if you use a map to estimate the range to the target, you do NOT have to worry about slope dope (slanted angle shooting). That is because a map gives everything in a flat plain, giving you distance without up and down changes, this is the distance in which gravity is acting on the bullet, and the desired distance to put into your scope.

Using a GPS is good for both pinpointing your exact location to use in conjunction with the map method, and it can also be used to tag target items in your AO. If you have the opportunity to patrol through your AO, be sure to take your GPS and mark any easily identifiable features. Like intersections, buildings, bridges, hills, etc. It is then trivial to determine the range (actually, the GPS determines the range) and its fairly accurate (depending on how accurate your unit currently is). This method can be extremely useful and of course becomes a great aid when making range cards and viewing an AO. This method also has the advantage of providing you the flat line distance, meaning you do NOT have to take into account slope dope when a range is given to you by a GPS.

Mk0 Eyeball

When all else fails, or when time is critical, all you have is your own eyes and your brain. How accurate can you be? Actually, pretty darn accurate. There are three things you can do to help you become better at estimating range with the naked eye: practice practice practice. You can practice walking down the street, pick an object, estimate the range and pace count it off. Or when driving in the car… estimate the range to a sign in front of you, then watch the odometer. Or better yet, when at the unknown distance range, estimate the range to the target BEFORE you calculate with mil-dots or use the LRF. These exercises can make a very big improvement.

Some things to remember when estimating range with your eyes

  • An object of a regular outline appears closer than a target of irregular outline.
  • A target that contrasts with its background appears closer than it really is.
  • A partially covered target will appear further away than it actually is.
  • If you follow the terrain with your eyes out to the target, you will tend to overestimate the range.
  • Observing over a smooth terrain such as snow or sand, you tend to underestimate the range.
  • Looking downhill makes the target seem further away
  • Looking uphill makes the target seem closer
  • If the sun is behind you, the observer, the target will appear closer.
  • And if the sun is behind the target, it is harder to see and appears further

When estimating, you can imagine football fields between you and the target, and that helps some people become more accurate. It also tends to be more accurate if you find an object half way to the target and estimate the range to it, and then double that range to get the range to the target. But again, the most important thing to do is practice

Duplex Reticle

Now, the concept of using a reticule in a riflescope to estimate range has been around a lot longer than the mil-dot reticule has been. The idea is that as long as you know the measurements of your reticule and know the size of the target, one can estimate the range. Let us use the Leupold duplex in a 3.5-10x scope as an example. It works something like this:

We know, from looking it up in Leupold’s catalog, that the thin opening of the duplex reticule covers 15″ at 100 yards when on 10x. So, if you are looking through your scope and your target and you estimate that the thin opening covers five feet (or 60″), then you simply divide the number of inches it covers by the number it covers at 100 yards (15″ in this case) and that tells you how many hundreds of yards. So, 60 / 15 = 4, or 400 yards. Of course, you can go from the crosshairs to the start of the thick part (7.5″ in this case) and do the same thing.

Now, I will show you a little more advanced, but easier to use method for a variable power scope and duplex reticule. Let us use the same 3.5-10x Leupold scope that covers 15″ in the thin opening at 100 yards. What you can do is figure out what the thin opening covers at the zoom power ranges in the equivalent range in hundreds of yards. The idea is to use the zoom power as your range finder. So, by using some math, we determine that the 15″ at 100 yards covers 150″ at 1000 yards (10x setting). Well, that is a fairly large size, so lets take the distance from the crosshairs to the start of the thick reticule which is 7.5″ at 100 or 75″ at 1000 yards. Now, this is a bit more reasonable, representing a 6’3″ person which is fairly tall, but at least something you could estimate. So the idea is to zoom in your scope until the area between the crosshairs and the thick part covers 75″, when it does, look at the zoom ring and multiply it by 100 (just add two zero’s on the end) and that is the range to the target. For instance, if you zoom in until it covers 75″, then look at the power ring and it is half way between 6 and 7, then the target is 650 yards away.

This method can be used on all reticules; you just have to know the measurements (listed under reticule subtensions in the catalogs). This works well on reticules that have many tick marks like the Burris ballistic-plex. You can then have more options to use for your range estimation. In fact, if you do not want to learn the mil relation formula, here is a little trick:

2nd Focal Plane scopes and Mil-dots that are calibrated for 10x

Lets apply the above method to a zoom scope that is set to be mil correct at 10x and is a 2nd focal plane scope (reticule stays the same size). We know that a mil is one measure of unit at 1000 measures of unit. So, if we want yards, we know that at 1000 yards, a mil will cover one yard. That makes it very convenient to estimate range on a 6 foot tall target. All you have to do is zoom in the scope until a 6 foot tall target measures exactly 2 mils. Then read the zoom on the scope, and add the two zeros. So, if you are milling a 6ft tall man and you zoom in the scope until he fills in right at 2 mils, then look at the power ring and its right on the 8, then the target is 800 yards away. Pretty slick eh? You can cut that down to 1 Mil – 1 yard (about waist to top of head) and do the same.

Conclusion

Well, we covered several alternative means of range finding here, hopefully some will be useful to you. I will probably add more as time passes and I discover, am told about, or remember other techniques. Feel free to send an email with your own suggestions!!