Distance estimation

4

4V50 Gary

Staff
As we all know, bullets do not travel in a straight path and follow a curved trajectory. By estimating the distance, we can either adjust our sights or more primitively, our hold such that our bullet will strike the target. In the Civil War, Confederate sharpshooters and artillerymen on both sides were trained in distance estimation. After some practice, a soldier became adept; or was washed out. In artillery, it was critical because the artilleryman not only had to calculate the distance, but the time of flight so he could adjust the fuse so that it will explode over target and maximize the injury inflicted on the foe. Sometimes an aid in the form of a stadium (period vernacular) was used.

https://i.ebayimg.com/images/g/qFMAAOSwg5tdETNG/s-l300.jpg

I just found this on pages 74-5 of a memoir andWW II book, Survivor, by George F. Schneider:

"On a training mission in the woods, we were fired upon (with blanks) by a machine gun that was visible at an unknown distance. Our assignment was to estimate this distance. Estimates ranged from lows of 50 feet to highs of a couple of hundred. While we were estimating the distance, our lieutenant sent someone out to pace the distance. I remembered that in high school, my science teacher, Mr. Haight, had shown us a track to estimate distance to an object. I applied his simple mathematical maneuver using only my finger and eyes. Holding my arm stretched out in front of me, I lifted my finger and visually placed it on the tree. Alternately, I blinked my eyes and announced that the distance was 145 feet. I endured laughter and howls from my comrades until the scout returned to announce that, according to his pace, the distance to the machine gun was 145 feet. Their taunting hoots immediately turned into exclamations of incredulity, and I was urged to explain my seemingly magical technique to the platoon. First, I had to find an object adjacent to the machine gun. That object needed to be a known dimension. In this instance, I choose a particular species of tree because all of these trees in this area were about the same size in trunk diameter and height. I zeroed my fingertip in on the tree adjacent to the machine gun. As my vision shifted from right eye to left, my finger moved left to right across the tree trunk. Knowing the diameter of the tree, I was able to extrapolate the distance my finger was moving. I then multiplied that number by 10 and arrived at a distance of 145 feet. The distance you see your finger move gives you a good estimate if there is a reference material of a known dimension such as bricks on a wall or a vehicle. The multiplication by 10 is general and dependent on the length of your arm and the interpupillary distance between your eyeballs."

Next time I go I'm going to give this a try. Funny thing about bricks, American brick manufacturers did not standardize brick size until Herbert Hoover was Sect. of Commerce. Prior to that there were probably 32 different brick dimensions being made and sold in America.

Let me know what you guys think of this principle for range estimation. I know lasers are easier, but sometimes the batteries give out (and I don't have a laser range finder).
 
Ol, I'll bite, ypu never explained what the device in the picture is; maybe the "stadium", but you also never explained its use. I am certain that the string wrapped around it is weighted an acts like a plum bob......
 
pwc said:
Ol, I'll bite, ypu never explained what the device in the picture is; maybe the "stadium", but you also never explained its use. I am certain that the string wrapped around it is weighted an acts like a plum bob......
Click to expand...
I'll show my ignorance and take a guess at how it works.

I think the string is nothing but a lanyard. The device works like the slider on a long-range rifle sight, but the function it performs is the same as the dots or stadia lines on a scope reticule. My guess is that you hold the device up more or less at arm's length, find an adult male who is standing up, and adjust the slider until the man fills the aperture (or until the aperture properly frames the man, to express it differently). The line number the slider aligns with is the distance in yards.

[Told you -- wild guess]

[Edit to add] I was actually close -- except that the string serves a more important function:
https://www.lordrivers.com/product-page/rifle-stadium-victorian-stadiametric-rangefinder
 
The multiplier must be x100.....why a difference in infantry (left side) and Cav (calvary?) on the right?

Are infantry smaller at 800 yds?
 
I am certain that the string wrapped around it is weighted an acts like a plum bob......
Click to expand...
Nope - the string is a known length. Think along the lines of triangulation.

https://www.papercartridges.com/stadia.html


I knew about the Holtzapffel name as their workbench is the defacto style for almost all cabinet makers - even though today's' modern shops that utilize power tools.(IMHO- only)((others will claim Roubo is the defacto))

The debate between which workbench - Holtzapffel or Roubo - can get every bit as heated as the debate between slow and heavy (.45 acp)vs fast and light(9mm)...

An interesting little tool from a fine old name.
 
TXAZ wrote:

Quote:
Originally Posted by RaySendero View Post
A Mil-Dot scope would be much easier.
Click to expand...

Or a laser range finder or auto-ranging scope.
Click to expand...


We use lazer range finders for our lease shooting houses.
Range various trees and other markers - Write distances on wall.

I learn on a Mil-Dot and basically use the same principle of OPs range estimator.
A nice trophy buck around here measures about 15" from small of back to bottom of chest.
If put the scope's horizontal cross hair on the deer's back and count the dots down:
at 100 yds, 3.5 dots.
at 200 yds, 2 dots.
at 450 yds, 1 dot.

Now, a medium size doe is problematic as would be a 5" man in the OP estimator.
I ranged such a doe with my dot count to be 350 yds.
The actual distance was only 285 - a 23% error.
 
Before range finder's friend and I stepped off everything for the sake of estimating range to figure how many steps per hundred we stepped off the 100 yd range at a gun club. We estimated everything to 300yds and got really good at that. Today I have a range finder I seldom use. I limit myself to 300- yds and seldom that far Zero for MPBR at a 6" or sometimes an 8" target and forget about range so long as I can estimate it pretty close. Check myself with the rangefinder now ad then.
 
Measure the angle extended by object of known size. The distance of the object can be calculated. This principle has been in use probably since the ancient Greek.

-TL

Sent from my SM-N960U using Tapatalk
 
When teaching new ie troops how to figure the pace whole on the foeld, we would take them to the football foeld and pace off the the 100 yds 3 different times. They already knew the length of their stride. A lottle longer downhill, a little shorter uphill.

Then just for grins and giggles we'd blindfold them and have them walk down the field with a guide to prove to them which is their strong side. Everyone viers left or right. Left alone they would end up facing the bleachers when we stopped them and took off the blindfold. Noone ever made it to the 100 yd line. That's why when walking in strange terrain. Always get two points of reference (just like lining up gun sights) along your route. When you get to the first, pick another "front sight".
 
You held the string in one hand and beneath the dominant eye. You extended the stadia for the length of the string and looked at the object. The scale was then moved until the object fit it. One side was for a man (5'6") and the other for a cavalryman. You then read the number engraved on the side and it gave you the approximate distance to the man/cavalryman. Hans Busk has illustrations in his book (The Rifle and How to Use It) which were reproduced in my first two books.
 
A Mil-Dot scope would be much easier.
Click to expand...
Certainly, if one had one at their disposal. Mil-ran was used by German tanks in WW II. A good discussion may be found in the book Panzer Gunner. Canadian fellow is sent to the Vaterland (he had Germanic origins) and found himself drafted and serving in the 7th Panzer Division when it invaded Russia. Anyway, he has a great description on the use of the mil-ran sights for distance estimation. Post war he returned to Canada and got funny looks when he responded to inquiries as to what unit he served with.
 
pwc said:
The multiplier must be x100.....why a difference in infantry (left side) and Cav (calvary?) on the right?

Are infantry smaller at 800 yds?
Click to expand...
"Infantry" and "Cavalry" refers to the target, not the user. The calibration is for an infantry soldier to be 6 feet high, and for a cavlaryman mounted on a horse to be 8 feet high.
 
During my career as a machinist/mold maker,I used tools such as sine bars and plates,triangulation to calculate angles,positions,points of tangency,etc.

All those skills were just part of my thought process.

On my own,I figured out how to use my known duplex size with a known target size to range. When I described what I had figured out toma knowledgable rifleman,he laughed and congratulated me for figuring out the Mil-Dot principle.

I find it very useful to know the "measurement" of any reticle feature to use.

That's also part of my preference for fixed power scopes. They keep it simple.

Given a rifle with a 2700 to 3100 fps trajectory,and what my scope duplex gives me,I can estimate range on game animals close enough to place a shot to someplace close to 400 yds. Then my ranging method tells me "Get closer"

Someplace in either the Infantry Handbook or the Ranger Handbook (or both) it describes using details of the front sight (at that time,the M-14) to estimate range. The width of the sight blade,the width between the sight ears,etc.

I have a laser range finder,a pretty good Leica....but I quit carrying it for most hunting.

I've considered getting a military binoculars with a reticle..that would be nice.

I just gave up on the idea of spotting wth binocs,switching to a laser range finder,then switching to my rifle. Too much time and motion.

If I now my duplex is approx. 2 mils,post to post, I know an antelope,brisket to whithers that fits the duplex is close enough to 200 yds. Center crosshair to post tip,its pretty near 400 yds,and maybe too far.

I balance my trajectory against my range estimation,both for distance and precision. Its a great,practical tool to immediately have in my scope all the time.

The trick is to use it enough to be at a level of "unconscious competence" all the time. I can use it without thinking about it.
 
Last edited:
There was an article by some old FBI on how to use Duplex (Leupold 3x9 Vari II) for range finding. The Soviets did the same with the front sight blade of their M91/30.
 
Most duplex reticles (check yours) subtend angle of 60 moa between the thick lines, if you can set the magnification to 1x. Say a man's shoulder width (18") fits between the thick lines at magnification of 5x. D is range in hundred of yards.

60 / 5 = 18 / D
D = 18 * 5 / 60 = 1.5 hundred yd = 150 yd

This is a close approximation. The actual range is 5% shorter, or 142yd.

The device in discussion works in the same way.

-TL

Sent from my SM-N960U using Tapatalk
 
Way back in the stone age I got taught a rule that worked reasonably well, though I no longer remember the formula.

It was a general thing, and based on the tendency of most people to estimate things as further away than they really were. You too the guess and then did something like multiply by 3 and divide by 5 (or something like that) and surprisingly, it was often fairly close to the actual distance. Not always, but often.

Another place one finds a "distance compensator" is in the sights of European milsurp bolt actions. US shooters often find frustration at how these rifles often "shoot high" especially at 100yds. Many nations "zeroed" at 300m and additionally, soldiers were taught to aim at the enemy's belt buckle. This method increased the odds of a torso hit, if the soldiers range estimate was off a bit.

Today, with range finding scopes, trajectory compensators, and lasers, few people need, or have the skill in their heads to do what the old timers had to do. Considering what they had to work with, some of those old boys could really shoot! :D
 
Most duplex reticles (check yours) subtend angle of 60 moa between the thick lines, if you can set the magnification to 1x. Say a man's shoulder width (18") fits between the thick lines at magnification of 5x. D is range in hundred of yards.
Click to expand...

I have not noticed any industry standard. IIRC,the fixed Leupold 4 x and 36mm obj 6X subtend 12 in at 100 yds.

My 6x x 42 mm measures about 7 in at 100 yds,post oint to post point.

I just look at a 1 in grid sight in target.downrange,with one on the bench beside me.
Often online you can find dim dwg's of reticles in tech specs

I know folks love variables,and that's OK.

For myself,a fixed power leads to less distraction and fiddling. My scope is always the same. The ability to make a range estimation in three seconds,maybe 5,while looking through the scope....no motion,no fumbling between binoculars ,rangefinder, rifle....

I generally consider 400 yds my outer limit. Settng a arget at a lasered 300 yds and dead zeroing puts the bullet at the tip of the hanging post at 100 yds,and on the tip of the low duplex at 430 yds.

If I call antelope 14 in body height,fitting a 7 in duplex s 200 yds.

I can interpolate(Kentucky) well enough to place a shot with my trajectory to 400yds. Sure,there is some error. But I get close enough that a 3050 fps MV is forgiving,up to a point.

I recognize at longer ranges,a 25 yd ranging error is a deal breaker. I don't shoot that far.

6X sees well enough for me to easily bench all my shots well within the orange sight in diamond,with change to spare.at 300 yds.

I just don't see what more I need in a hunting package.
 
You must log in or register to reply here.
Back
Top