Range Estimation Methods & Techniques

RANGE ESTIMATION PART I:

RANGEFINDERS

"That prairie dog is at precisely 327 yards...and next time you get to carry this SOB!"

Rangefinders actually aren’t a brand new thing. They’ve been around for better than a century. Unfortunately, they were coincidence rangefinders, also known as stereoscopic or parallax rangefinders. These worked by triangulation, just as you would use with a compass, with a prismed lens on each end of a long tube with a central eyepiece. The longer the tube, the more accurate the rangefinder.

Sure, they worked great and could be accurate indeed, but you needed a nice battleship or an artillery battery to lug them around with. They weren’t very well suited for use by the average infantryman or hunter.

Years ago, before laser rangefinders, when pterodactyls ruled the skies, I actually had a commercial sporting coincidence rangefinder. It was about a foot long and lightweight enough, but when it came down to ranging it performed in a manner experts refer to as a “big pain in the butt”. You absolutely needed a straight line to range on, and it seemed like you had to recalibrate the fool thing every other day.

Now, I have a laser rangefinder. Yes, despite all my preaching about not relying on things that use batteries in the field, I have and use a laser rangefinder all the time. But remember Murphy? A few years back, I lost my

Bushnell rangefinder out in the middle of a hay field despite the aptly-named dummy cord. Long story.

Fortunately, this turned out to be a good thing. I replaced it with the Nikon ProStaff 550 and I am much happier with that rangefinder. It’s only rated to 550 yards, but I’ve occasionally gotten ranges out to 750 under good conditions with it. It’s light and compact and handy, measures for yards or meters (me and my furrin’ military rifle scopes), and also calculates actual ranges on up and down angles, always handy in the mountains. I can highly recommend it.

Fits in the palm of your hand.

In hindsight, I would have gotten a 1200-yard model, but they cost about twice as much and it would have just been for playing with my toys. The average hunter has no business shooting beyond 300 yards, if that.

I’m not to person to explain the inner workings of any electronic device. There’s stuff like diodes, non-visible wavelengths, infrared spectrums, nano-seconds and nano-meters, and, I believe, dilythium crystals involved. (Ach, she canno’ take it, Cap’n. The toilets are backed up in the warp drive now!) Ben says it’s magic, but I lean more towards sorcery.

Anyway, here are just a few observations I’ve noted from using a laser rangefinder for several years now, mostly in hunting situations. They apply to pretty much any laser rangefinder. I hope some of these notes may be of

use to some of you. Just my opinion and observations though; worth what you paid for ‘em.

As with your rifle or binoculars, the steadier the better. I often carry a walking stick while antelope hunting out in the big wide open, and can brace the rangefinder on the top of that to steady it. Going prone, sitting down with your elbows on your knees, bracing on a fencepost, whatever allows you to hold the range-finder steadier is going to make it much easier to get a precise reading.

It can be hard to range an actual animal, especially as range increases, as their pelt kind of soaks up the laser light rather than reflecting it. I often find it’s more effective to laze a juniper, clump of sagebrush, big rock or patch of bare dirt in close proximity to the critter.

Reflectivity is a weird thing. They say the more reflective, the better. I’ve found that ain’t necessarily so. I have a helluva time lazing my own truck, which is dark blue. I can laze and laze, trying different areas and the shady side, and get no reading off it. An instant later I can laze my black range bag sitting on the ground fright next to the truck or a nearby sagebrush and get a good reading right off the bat.

In bright sunlight, a rangefinder loses a bit of performance. On the other end of the spectrum, fog and mist disperses the laser and degrades performance to varying degrees. Dropping your rangefinder down a steep, rocky slope into a mountain stream really degrades performance.

Rangefinders work well in the dark. Unfortunately, the commercial models have an LED read-out inside the tube which you can’t see in the dark. I’ve found I can laze in very little light, then point the rangefinder at the sky and be able to read the LED against that lighter backdrop. Thus I can set up on my shooting position long before daylight and laze various objects to determine general ranges and have a pretty good idea of what I’m dealing with well before shooting light rolls around.

Of course, I’m not talking an overcast moonless night when it’s blacker than the inside of a cat; you have to be able to see what you’re lasing too. You have to have some light. This paragraph just made me think I should try using my rangefinder under a full moon some night. I’ll bet it would work. Update at a later time.

In a tactical situation, however, it should be noted that laser rangefinders show up bright and clear to someone with a night vision device, pointing a straight line right back to your location.

Angle has some effect, too. You want to try to laze something as close to 90-degrees flat on as you can. Like a bullet ricocheting at a flat angle, the laser kind of can too.

The more solid the object ranged the better. If you have a choice of say an exposed rock, a juniper, and a clump of sagebrush you’d obviously try to laze the rock first since it will reflect the most light without diffusing it like the multiple small branches of a sagebrush.

Tall grass between you and the target can be a real pain in the butt, too. You have to make sure you’re high enough so that the laser doesn’t hit those barely visible stalks in your field of view and give a false reading. This is why it pays to be able to range-find by eye as well, to know when you’re obviously getting the wrong range.

A field of fresh snow is also a problem. Look for some kind of dark object like a tree, bush, or dead Commie which stands out in sharp contrast to laze.

One of the best things you can do with your rangefinder is to just carry it along with you on your walks. Estimate the distance to some point by eye, and then check the range with the laser to see how accurate (or inaccurate) you are. Constant practice playing like this will do wonders for calibrating your own Mk. I Mod 0 Eyeball if you have to estimate range the old-fashioned way someday.

I don’t know if this is worth anything, but I am more used to hunting wide open spaces so I tend to greatly over-estimate ranges when I’m in the dark timber high up bow hunting. I look at a certain tree up ahead along the trail and think, “That’s about 40 yards.” Nope. Nikon says 23. D’-oh! In the big wide open, however, I tend to under estimate range. That’s why it’s so good to take your rangefinder along on your hikes and test yourself.

RANGE ESTIMATION PART II: GUESSTIMATION

No matter if you’re packing a poodle shooter or a real rifle, getting a hit at long range requires accurate range estimation, which has traditionally been one of the hardest things for a solider or hunter to learn.

It goes back to ballistics why this is all so important at ranges beyond your battle sight zero, ranges which are being encountered every day in Afghanistan where the average engagement range in the hinterlands is 500 meters.

Even being 50 meters off on your estimate makes a big difference when you get to shooting “way out past Fort Mudge”, as Jeff Cooper would say. Say you’re shooting a .308 at a target you estimate to be at 400 meters, but it’s actually 450 meters. Due to that seemingly small error, your trajectory at the target will be a full foot lower than your aim point. Still close enough for minute-of-badguy (shoot him in the nards) but not close enough for a shot into the vitals of a deer.

Further out, estimating a 650 meter target to be 600 meters, you’ll be shooting two feet low. A fifty meter error at 800 yards is a 32-inch difference in your bullet’s trajectory.

As Dirty Harry says, “A man’s got to know his limitations.” Which is why I consider myself at best a designated marksman; I don’t shoot over 600 meters and that’s the limit of the BDC on both my scopes anyway. I might try a 700 meter shot with hold-over in an emergency, but that would be the absolute max, and my first shit probability would be less than 50%..

At those ranges, a real sniper, which I’m not, with a real sniper rifle, which I don’t have, is just coming into his own. I leave that to the experts. I’m not that guy who wants to “make a 1,000-meter shot so I’ll look cool on the Internet”.

Nowadays, we have very affordable and compact laser rangefinders as well as the Mil-Dot system in some optics. But let’s say you don’t have a scope with Mil-Dots because you’re not a sniper type. Neither do you have a laser rangefinder. Or the battery in you rangefinder goes dead in the cold or you drop the thing down a scree slope into a creek or the darn thing just stops working.

I had a GPS for all of two weeks. I accidentally dropped it on a gravel road once and it never worked again. Good thing I wasn’t five miles back in the mountains and depending on the thing to get me home. As for myself, I have always been adept at land navigation via map and compass, especially terrain association here in the mountains. I’m weird enough that I look at topo maps and Google Earth for fun, finding good places to hunt or interesting places to explore.

If you are good at, or become good at, land navigation, a map can be right handy to estimate range pretty close. Here’s what I mean with the following example.

Your position is in the center of the black circle as you sneak through the low point of the saddle in the ridge to take a peek at the country beyond. You see Bruno the Great Wapiti come ambling out of the woodline down by the creek bottom, the middle of the red square. With a piece of paper or any straight edge you can put a mark on, you measure the distance from the circle to the square and then slid your straight edge down to the distance scale at the corner of your map and measure it. The blue line represents this. So, ol’ Bruno is about 800 meters away, too far for a shot. Of course, the larger the scale of the map, the better this works.

The most common unaided eyeball method of range estimation is the “Unit of Measure” method, which was the first one taught when I was in the service, going on the theory that every red-blooded American boy should have been on a football field and know how long it looks. One hundred meters is a football field with both end zones included.

100-Meter-Unit-of-Measure Method. To use this method the sniper team must be able to visualize a distance of 100 meters on the ground. For ranges up to 500 meters, the team determines the number of 100-meter increments between the two objects it wishes to measure. Beyond 500 meters, it must select a point halfway to the object and determine the number of 100-meter increments to the halfway point, then double it to find the range to the object.

FACTORS TO BE CONSIDERED IN DETERMINING RANGE BY EYE

OBJECTS APPEAR CLOSER THAN THEY REALLY ARE

OBJECTS APPEAR FURTHER THAN THEY REALLY ARE

The target—Its clearness of outline and details.

When most of the target is visible and offers a clear outline.

When only a small part of the target is visible or is small in relation to its surroundings.

Nature of the terrain or position of the observer.

When looking across a depression, most of which is hidden from view.

When looking across a depression, all of which is in view.

When looking downward from high ground.

When looking upward from low ground.

When looking down a straight, open road or along a railroad track.

When field of view is narrowly confined, as in city streets, draws, or forest trails.

Light and atmosphere When looking over uniform surfaces like water, snow, desert or farm fields. In bright light or when the sun is shining from behind the observer.

In poor light such as dawn and dusk; in rain, snow, or fog, or when the sun is in the observer’s eyes.

When the target is in sharp contrast with the background or is silhouetted by reason of size, shape, or color.

When the target blends into the background or terrain.

When seen in the clear atmosphere of high altitude.

The British and former Commonwealth nations still use the appearance method. And have been doing so for a long time. I first became aware of it from an episode of Sharpe’s. It’s mentioned in American manuals, but it’s vague as hell and doesn’t sound too useful, not made simple and easy like the Canadian Army except below.

The appearance method compares the way an object looks at 100 metres and at greater distances. By comparing the appearance of a man in several positions—at 100, 200, 300, 400 and 500 metres—observers can establish a series of mental pictures. They will find that, as distances increase, a man's figure becomes smaller, his outline becomes increasingly blurred and his other features gradually fade out. The following may be used as a rough guide to determine the distance a soldier is from the observer:

a. 200 metres—all parts of the body are distinct;

b. 300 metres—outline of the face becomes blurred;

c. 400 metres—outline of the body remains, but the face is difficult to distinguish;

d. 500 metres—the body appears to taper from the shoulders; movement of the limbs can be observed;and

e. 600 metres—the head appears as a dot with body details invisible and tapering noticeably.

That’s pretty easy to remember with some practice. In the same way, the appearance of other familiar objects can be learned. For instance, I know if I can no longer see my brother’s willy, he is beyond 500 meters.

This is from the 1942 Red Army sniper manual, but I don’t find it very useful. I mean “400-1000” meters or “8-11 klicks” is not real precise. Can

you be a little more vague?

Something else I never heard mentioned, except at an Appleseed shoot, is the use of the front sight of your M1/M14 to measure range fast and easy for the average rifleman. If the body of the target is as wide or wider than your front sight post, he is within your 250 meter battle sight zero and you don’t even have to worry about elevation, just hold center mass and shoot.

The Brits took this method a step further, using the front sight blade of the standard Lee-Enfield service rifle to help measure range.

INFANTRY MANUAL, 1942

HOME GUARD DEFENSE MANUAL, 1941

You can figure out the same thing for your own rifle, whether using open sights or a scope. I placed man-size silhouette targets at known distances in 100 meter intervals then move around sighting in on them. You may find, for instance, that the small part of a duplex crosshair up from the horizontal wire is the height of a standing man at 100 meters or that the thick portion of a duplex reticle covers the width of a man-sized target at 300 meters, or whatever. It’s something you have to figure out in practice not in theory.

I was lucky with my German Hensoldt Z24 scope on my FAL, as it has a goofy multi-line vertical post reticule. I figured out how many lines were needed to span the width of a silhouette target at what ranges.

I don’t have a manual for my old Z24 Zielfernrohr fur Sturmgewehr (1 each), and my German isn’t good enough for it to be of much help if I did, but I have found that at 300 yards, a man-sized silhouette fills all the pointer lines. At 500 yards, a silhouette fills three of the lines.

Know your individual weapon.

For quite some time, a common military method used in range estimation was averaging. Every man in the squad estimated the range to the target and the total was averaged. This can provide a more accurate estimation, but only if the individuals at least generally know what the hell they are doing.

One should know one’s own pace count, the average number of steps required to cover 100 meters, counting each time the left foot hits the ground. Mine is 65, and pacing distances to place targets I find, upon verifying with the range-finder, I am almost inevitably within 10 meters of the desired distance.

With a pace count, in a static position, you can figure ranges with a pretty decent amount of accuracy. Of course, this method won’t work too well in a tactical situation. At any rate, you can pace out the ranges to various landmarks in your field of fire, and these landmarks provide “key ranges” from which you can much more easily estimate the range of any target which appears in the vicinity. I’ve used this hunting before, pacing and marking and then setting up on a good vantage point well before dusk to wait for the deer to come out.

Something I’ve always used is what I call the fenceline method. Growing up on a farm and in farming country, I kind of take for granted the size of a piece of land; quarter section, half section etc. Fenceline to fenceline on a quarter section field is exactly a quarter mile, or 440 yards. For the half sections it’s a half mile or 880 yards.

I have heard often of knowing the standardized distance between telephone or powerline poles, which is pretty much the same thing. It does work pretty well, where such things are present. I used it on antelope once by counting highline poles. If the target is in between the fencelines or power pylons, the bracketing method can be used.

Bracketing. If the target is known to be located between two reference points of known distance then the bracketing method may be used. Simply add the two known distances (X and Y) and then halve the sum for a close approximation of the range. For example, if X is 1000 metres and Y is 600 metres, the sum is 1600 metres, halved is 800 metres, which is the range. The further away thetarget, the larger the bracket should be.

Obviously, if the target is visibly closer to X than to Y you would have to take that into account to get a more accurate fix, using more the key range method.

Here’s a few handy methods you can use if you have the distinct displeasure of someone shooting at your butt. These are, of course, the least desirable means to use, especially if the other guy knows a thing or two about shooting.

NOISE AND MUZZLE FLASHFLASH TO BANG

(Canadian Army Manual) Since sound travels through the air at a fairly constant speed (330 metres per second), it is possible to estimate the distance from a weapon that has been fired if the traveling time of the sound from the weapon is known. The traveling time is the period between observation of a muzzle flash, backblast, smoke or dust raised by the concussion and hearing the round being fired. The time can be measured accurately by counting at a rate of three beats

per second during the period. Counting starts as soon as the visual effects of the weapon firing are observed and cease when the report of the weapon is heard. The number reached will be the approximate distance to the weapon in hundreds of metres. If the count of eight has been reached when the report is heard, the distance to the weapon is approximately 800 metres.

CRACK AND THUMP

(No, crack and thump does not relate to being constipated in the field.)

When a bullet passes near, one hears two noises: first, the crack of the bullet passing, then the thump of the weapon being fired. The crack is heard before the thump because the bullet travels faster than sound. The thump indicates the direction of the weapon. The distance to the weapon can be estimated by timing the interval between the crack and the thump. The further away the weapon, the longer the interval between the crack and the thump. The time between the crack and thump at the following ranges is:

a. 300 metres — 2/3 of a second;

b. 600 metres — 1 1/3 seconds; and

c. 900 metres — 2 seconds.

If it only takes a quarter of a second, you’d better have bayonet your bayonet already fixed.

Undoubtedly the least desirable method of range-finding is the bullet hole technique. This comes into play when someone is not just shooting at your ass, but coming real close to outright hitting it.

After an enemy bullet parts your hair, you can find the bullet hole, hopefully in a wall or the dirt rather than your buddy’s head, and insert a pencil, stick, section of cleaning rod, etc. into the hole. The stick, of course, points straight back at the shooter. You either visually use the stick to determine the correct direction of the enemy or, better yet, stay hunkered down under cover and shoot an azimuth of the direction with a compass or GPS.

Then you can use the angle at which the bullet struck to get a rough estimation of the distance from which your opponent is firing. I got these angles using a ballistics graph of a 7.62x54R 174-grain heavy ball round’s trajectory, assuming some goat-smelling jihadist is firing at you with an SVD, PKM, Mosin, etc.

So, an example. You and your partner are sitting in the old barn marked “A”, minding your own business, warm and dry for once, and observing traffic on the road across the creek. Then a bullet whips past your head and into the wall behind you. Of course the first thing you do is hit the deck and stay there and say a bunch of bad words. After the cussing, you crawl over to the bullet hole, put a pencil in it, the angle of which indicates a 400-500 meter shot. Then you get a compass azimuth of 38-degrees (just an example: I’m not going into back azimuths and magnetic declination today) from the direction the pencil is pointing.

With the direction and distance plotted out, you can figure out on the map that the little bastard who took a potshot at you is probably up in the trees on that finger spur marked “B”. You can do roughly the same thing by Mk. I Eyeball, provided you don’t stick your head out to do so. At any rate, you have a pretty good idea where he’s at now so you can move to better cover and/or concealment to start glassing the area to find him.

I am very happy to say I’ve never had to make use of this method, although one time a nice mule deer buck tried to lay down suppressive fire on me with an old Russian Goryunov 7.62 machine gun. But that’s a whole other story.