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M3 binocular reticle explanation

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#1 adowns

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Posted 21 August 2018 - 04:12 PM

I understand the horizontal scale in tens of mils. But not the vertical scale.  All I can find is that it is graduated in hundreds of yards from zero to 2000 yards.  How is it used?

 

 

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#2 hallelujah

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Posted 21 August 2018 - 04:44 PM

See if this helps at all. scratchhead2.gif

 

https://www.ibiblio....dfs/TM9-575.pdf

 

Stan



#3 adowns

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Posted 21 August 2018 - 05:05 PM

Stan, thank you for the link.

 

If I understand the technical manual in the link correctly, it is how high to aim at far away targets.  I'm not sure how this would be any better than the rifle's own sights which can be adjusted for long ranges.  It may be that the soldier would keep his sights at the point blank setting and then aim at some object above the target identified through the binoculars.

 

Also the reticle could only be used for a certain type of ammunition whose ballistics are known and match the bullet drop indicated on the reticle.



#4 ThatGuy

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Posted 04 September 2018 - 08:53 PM

Hello,

The vertical scale on the right is graduated to 2,000 yards, read top to bottom. This was used to determine the proper sight setting for .30-06 calibre weapons. The method is complicated, and the scale is not useful unless intending to utilize indirect rifle or machine gun fire. I will detail it in the last paragragh. The horizontal line on the bottom is marked in 10 mil increments, 1=10, 2=20, etc., to determine adjustment for direct fire from larger weapons such as mortars, rocket launchers, tanks, artillery, etc. The two horizontal lines in the middle above the bottom line are 5 mils apart, and are used as a ‘crosshair’ or a reference point for placing over the target. The scale on the left is 5 mil increments to adjust indirect fire vertically.


Infantry would not have used the binoculars in place of the sights on their rifle, the 2,000 yard scale was used to determine the proper sight setting for infantry weapons to fire on a target that cannot be seen clearly at long ranges. The scale directly coincides with the impact point of a .30-06 bullet accounting for the parabolic arc of the bullets flightpath at a known distance. (There is a separate formula for determining distance/size of target/mils, I will post that separately.) Say you are ahead of your infantry platoon and observing a machine gun nest in WWII. Your platoon is 900yds from the nest, but cannot see it. How can they fire on a target they cannot see? By using the 2,000 yard Eames Scale (that is what it is called). You take the distance your platoon is from the target nest, 900yds, and put that tick mark on the scale directly on top of the target. From there, look up and down the scale and find an object which is visible to the platoon, let’s say the base of a tree on the 600yd tick, and have the platoon set their rifles to 600yds and fire at the base of the tree. They are firing at an arteficial target. Due to the parabolic arc of the bullet, even though they are aiming at the tree with 600yds set on their rifles, the bullet will hit the target machine gun nest at 900yds.


Edited by ThatGuy, 05 September 2018 - 02:21 PM.


#5 ThatGuy

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Posted 05 September 2018 - 02:14 PM

This is the formula for determining mils/size of target/distance.

 

If you know any two, you can find the third. It is basic trigonometry.

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Edited by ThatGuy, 05 September 2018 - 02:15 PM.


#6 Pinewood

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Posted 05 September 2018 - 02:48 PM

Hello That Guy,

 

The Eames Scale puzzled me, as well, when I first saw a US Army binocular's reticle.  I had an understanding of its use but yours was an excellent explanation.  I have never had to order indirect fire on an enemy, so its exact use slipped from memory.  The Eames Scale was used in US Army binoculars for many decades, so it was considered useful.

 

The mil scale can prove useful to hikers as well as hunters.  Should a map give the height of a church tower, for instance, one can calculate the distance.  

 

Clear skies,

Arthur Pinewood


Edited by Pinewood, 05 September 2018 - 02:58 PM.


#7 ThatGuy

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Posted 05 September 2018 - 09:06 PM

Wonderful, glad I could be of service. The Eames scale explanation is recorded in ‘The Rifle in America’ by Sharpe, page 687-688.

#8 hallelujah

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Posted 05 September 2018 - 10:16 PM

The Eames scale explanation is recorded in ‘The Rifle in America’ by Sharpe, page 687-688.

Thanks for the information about the book title.

Just ordered a copy of it from Alibris Books for $3.00 + S. & H. like-button.jpg

 

Stan



#9 ThatGuy

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Posted 05 September 2018 - 11:51 PM

It is an excellent book to have in general, and Sharpe’s writing style is witty, and very informative. Once again, glad I could help.

Honestly I joined Cloudy Nights specifically to answer this question. Maybe I’ll stick around and start looking up at night more!

Edited by ThatGuy, 05 September 2018 - 11:51 PM.



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