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Discussion Starter #1
I remember what a mil-dot reticle is, but in looking around at various scopes I noticed that Swarovski/Barrett offers their scopes in either mil-dot or ranging reticles... what's the difference?

Thanks a ton in advance!

Scatch Maroo
 

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It is manufacture dependent. The term "Rangin Reticule" can be used to discribe any reticule that can be used to estimate range (heck, if you know the deminsions of a duplex, you can estimate range with it). But what they more commonly are referring to is their proprietary reticule that can be used to estimate range. Some of them have horizonal bars that represent shoulder widths at various ranges, Others have a curved line that you use to measure the height of a man and it tells you the range, etc etc etc. So, to know exactly, you will need to look at that specific reticule from the manufacturer.

MEL
 

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mele is exactly correct from a dictionary definition point of view.

Let's look at an example that is different from a type MIL style range reticle.

For example here is USO's proprietary MOASCALE reticle:



Now lets say that you now that a wheel on a truck is 16" in diameter. Move the scale to the tire and read the mil subtension on the scale for the
wheel. Let's say that you read 4 moa or 2 marks on the above reticle.

The formula for the range is:

Range(yards) = Target size inches x 100 / MOA observed

So in this case the formula becomes:

R = 16 x 100 /4 = 400 yards. Now if we have prepared a come up chart for our round and the come up is say 10 moa, you have two options.

1. you can dial in 10 moa and hold the center of the reticle on the target.

2. you can put the 10 moa mark on the target and shoot without moving the knob.

Note that in this case both the knob and the reticle is the same scale, similar to the European system where both the reticle and the knob are in mils.
 

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Discussion Starter #4
Critter said:
Now lets say that you now that a wheel on a truck is 16" in diameter. Move the scale to the tire and read the mil subtension on the scale for the
wheel. Let's say that you read 4 moa or 2 marks on the above reticle.
Please forgive my ignorance, but I really want to learn how to do this...

When I move the scale over the tire, where do I place the scale onto the tire? Do I put the cross hairs (center of scope) on the top of the tire?

When you say the "come up" of the round, does that mean I should already have knowledge of how a particular round will shoot before I can actually make the proper adjustments?

Thanks a lot--it's incredibly interesting, just a little odd to grasp for the first time. :)

Scatch Maroo
 

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Heh Scratch........

in Critter's explanation he means.....place the reticule in such a way as to use the dots on either the verticle or horizontal cross hairs to measure (in those same dots) how many it takes to span the tyre....tyre being a KNOWN 16" diameter and the dots being a KNOWN 2 MOA each.

You can use any dots...eg.
put the end of the left side line of the reticul on the left side of the tyre and count the dots to the right covering the tyre....or, put the centre of the cross hairs on the top of the tyre and count the dots going downwards which cover the tyre....it dosn't matter.....just so long as you get how many dots to cover the tyre.......just as you would with a Mildot.

The crucial factors are..... knowing the size of the item you are ranging (The tyre) or some other item of known size near your target....eg. a car which is approximately 5 feet high.......and that the dots represent 2 MOA each.

Critter's example takes 2 dots to cover the tyre and 1 dot equels 2 MOA therefore we get a total of 4 MOA.
We then multiply the number of inches of the item of known size we are useing (the tyre) by 100.
16inches x 100 = 1600 we then divide this figure by the number of MOA, which in this case is 4 therefore 1600 divided by 4 = 400 (yards)

If we used the height of the car known to be 5 feet or 60 inches......and it was covered by 2 dots then....
60inches x 100 = 6000
6000 divided by 4 (MOA) = 1500 (yards)

You are correct about "Come up"...... it is the adjustment you make in cross-hair elevation for the range you have just calculated.
You will get the amount of adjustment you need in MOA from a balistic chart of the round you are using eg. .308 Federal Gold Medal Match 168 grain

Sorry if this is a bit "long-winded".....I hope it has made things clearer for you........cheers :)
 

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Discussion Starter #6
Kiwi said:
Sorry if this is a bit "long-winded".....I hope it has made things clearer for you........cheers :)
MUCH. Your examples reaffirmed the operation of the dots, although I did not know you could use them from any point. The idea of using mil-dots sounds really awesome, haha. Where can I get a ballistics chart... do I have to make one myself by shooting a specific type of round at the range, or does the manufacturer provide one? Obviously I'd have to produce my own if I handload a round no one else has charted.

Thanks everyone... I can't wait to explain it to others as if I'm some sort of seasoned expert... I just hope I remember how to cite it properly, and that they don't ask any technical questions. :lol:

Scatch Maroo
 

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Scatch Maroo said:
Critter said:
Now lets say that you now that a wheel on a truck is 16" in diameter. Move the scale to the tire and read the mil subtension on the scale for the
wheel. Let's say that you read 4 moa or 2 marks on the above reticle.
When I move the scale over the tire, where do I place the scale onto the tire? Do I put the cross hairs (center of scope) on the top of the tire?

You use the scale as a ruler to measure the angular displacement of the target, observing the number of MOA subtended by the scale. How you do it is up to you. Your method is acceptable.

When you say the "come up" of the round, does that mean I should already have knowledge of how a particular round will shoot before I can actually make the proper adjustments?

There are many ballistics programs that will calculate the ranges versus fall of the bullet given known or measurable values such as bullet ballistics coefficient(G1), zero distance, muzzle velocity, ambient conditions, wind, etc.

Note that this is not an easy subject, however the keyword is "Rifle External Ballistics", Look it up on the net, and you are right it is very interesting.



Thanks a lot--it's incredibly interesting, just a little odd to grasp for the first time. :)

Scatch Maroo
 

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Discussion Starter #8
Since everyone is in "Help the Noob" mode, would someone care to explain how a scope can help a person compensate for wind speeds? :)

Scatch Maroo
 

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Scatch Maroo said:
Since everyone is in "Help the Noob" mode, would someone care to explain how a scope can help a person compensate for wind speeds? :)

Scatch Maroo
1. If required always hold into the wind. If you have wind from the right hold right.

2. If there is a slight wind, hold about 1 to 1.5 moa at 300 yards.

3. If there is a windy wind, hold 2.5 to 3 moa at 300 yards. If more is needed then comp;ensate.
 

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Discussion Starter #10
Critter said:
1. If required always hold into the wind. If you have wind from the right hold right.

2. If there is a slight wind, hold about 1 to 1.5 moa at 300 yards.

3. If there is a windy wind, hold 2.5 to 3 moa at 300 yards. If more is needed then comp;ensate.
Could you explain what it means to 'hold" into the wind?

Scatch Maroo
 

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Hold means, you would need to hold your point of aim in the direction indicated. If you are holding right, you actually "aim" right. So if you are holding 1 MOA right at 300 yards (thats 3") then you will "aim" three inches to the right.

Holds are a critical part of long range shooting/tactical shooting.

The USMC Sniper School teaches proper holds at 100-700meters with a 600 meter zero, which I have found to be excellent knowledge. (and in my log books)

MEL
 

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Holding into the wind: A vector diagram

 
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