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Posted: 10/29/2004 7:51:51 PM EDT
I just got a 10x Super Sniper scope and am wondering if there is an explanation or formulas page.


thanks!
Link Posted: 10/29/2004 9:01:13 PM EDT
anything?
Link Posted: 10/29/2004 9:10:00 PM EDT
The dots in the mil dot scope subtend one miliradian of angle. (Radians are like degrees, just a different scale or method of measurement for determing angles.) If you have an object of a known height, you can use this fact to determine the range by seeing how much of a miliradian the object subtends using the principle of "stuff appears smaller the farther away it is."

The formula is

(Height of target (yards) X 1,000)/(Height of target in mils) = Range (yards)
Link Posted: 10/29/2004 9:11:09 PM EDT
Is it any different for a 3/4 Mildot reticle?
Link Posted: 10/29/2004 9:12:58 PM EDT
Here ya go...

Mildot how to.
Link Posted: 10/29/2004 9:18:31 PM EDT

Originally Posted By Fat_McNasty:
Here ya go...

Mildot how to.



Damn thats a good link! thanks mcgredo and Fat_McNasty!
Link Posted: 10/29/2004 9:22:36 PM EDT
Link Posted: 10/29/2004 9:31:03 PM EDT
Okay. Spell it out for those of us who are not familiar with the jargon, or are not mathematically inclined.

First off, subtend simply means to drop incrementally below a given reference point. Yes/no?
So each of the "dots" beneath the center(?) is used to measure what? The height of the object being viewed?

Or are we supposed to estimate the height of the object at a presumed distance and use the dots to estimate the actual distance?

How do you compensate for drop of the projectile?

Blah, blah, blah. I don't even know what fargin questions to ask.

Is there a way to simplify this process so I can understand it without boring myself into a catatonic state?

I've got a couple of mil dot scopes that I've never even used because I haven't bothered to take the time to figger it out.

Someone he'p a challenged brutha out !
Link Posted: 10/29/2004 9:33:24 PM EDT
Hmmmm. Got some reading to do.
Link Posted: 10/29/2004 10:12:41 PM EDT
Ok, I'll try to shed a little light on it for you.

1 mil = 3.6" @ 100 yds.
1mil = 7.2 " @ 200 yds. and so on

The actual height of a target is just that -the height . A 6' man is 6' at any range, he just looks smaller at longer distances. Therefore a 6' object will subtend 10 mil @ 200 yds and 4 mil at 500 yds. 1 mil = 18" at 500 yds.

You must know the ballistics of your cartridge in your rifle for the most accurate predictions. If you have your rifle zeroed at 300 yds. and drop is 12" at 500 yds. from this zero you know that each mil at 500 yds. equals 18" you would holdover by .666 mil ideally. Realistically .6 or .7 mil will get you close enough on a man sized target center of mass.

To help make a chart in 50 yd. increments starting at 100 yds. 100 yds. = 3.6" 150 yds. = 5.4" and so on. 3.6" x 1, 3.6" x 1.5 and so on.

There is a product called the Mil-Dot Master available at SWFA IIRC that makes it easy to calculate. But in order to use mil-dots you must know the size of the target and be able to judge the number of mils to the nearest tenth of a mil accurately.
Link Posted: 10/29/2004 10:27:54 PM EDT
The mildots are used to determine range. Adjusting for bullet drop is a completely different problem that depends on the round used.

Everybody is familiar with degrees--360 degrees to a circle. Right angles are 90 degrees. And so on. There are other ways to measure angles, though. "Radians" is a popular technique because it makes some math easier. There are 2 * Pi radians in a circle or roughly 6.3 radians in a circle, just like there are 360 degrees in a circle.

The centers of the dots in a mildot scope are 1 milliradian apart, ie 1/1000 of a radian.

When you look at something up close, say a six foot man at 100 yards, it takes a certain angle from his head to his feet. Move him back 100 yards more and he appears smaller, because he takes up less of an angle from head to toe. ("Subtends" less of an angle.)

Suppose you know a man is 6 ft tall. You measure the angle from his head to his toes. Because you're a smart guy, you can use these two facts--his known height and the angle--to determine how far away he is.

There's some basic trig involved. First of all, there's something called "tangent". In a right triangle, that's the ratio of the lengths of the two segments at right angles to each other.

| A
____|
B

In this case, iimagine there's a line from the end of B to the end of A, forming a right triangle. That line is called the "hypotenuse". There's an angle formed between B and the hypoteneuse. Call it "theta", because it's traditional.

What's the angle? Depends on what the lengths of the two legs of the right triangle are. But if you know how long the legs are, there's only one possible angle theta could be. What's more, if you have two triangles that have the same ratio between the legs, the angle theta is always the same.

The greeks noticed this and came up with the idea of "tangent". Tan for theta is in this case A/B.

So we can write the equation TAN(Theta) = A/B

Suppose we know A. In that case we can solve for B, B=A/TAN(Theta).

This is the basics of ranging with a mildot. Think of the A leg as being the height of the target, and the B leg as being the distance to a target. We know A, We know theta, and we can determine TAN(theta). The only unknown is B, the distance to the target, and we can use some basic algebra to determine that.

As it turns out, TAN(1 miliradian) = .001, TAN(2 miliradian) = .002, etc. So, using the formula above, TAN(Theta) = A/B, we can put in names for the values we're dealing with:

Height in miliradians * TAN(.001) = height of target / distance to target

height in milliradians * .001 = height of target / distance to target

distance to target = (height of target * 1000)/ height in milliradians

So suppose we have a 6ft guy. We look at him in the scope and discover he takes up 4 radians of angle.

distance to target = (2 yds * 1000)/4
distance to target = 500 yards

He starts running away. A few seconds later he takes up only 3 miliradians on the scope.

distance to target = (2 yds * 1000) /3
distance to target = 666 yards.


Link Posted: 10/29/2004 10:41:05 PM EDT

Originally Posted By mcgredo:
The mildots are used to determine range. Adjusting for bullet drop is a completely different problem that depends on the round used.

Everybody is familiar with degrees--360 degrees to a circle. Right angles are 90 degrees. And so on. There are other ways to measure angles, though. "Radians" is a popular technique because it makes some math easier. There are 2 * Pi radians in a circle or roughly 6.3 radians in a circle, just like there are 360 degrees in a circle.

The centers of the dots in a mildot scope are 1 milliradian apart, ie 1/1000 of a radian.

When you look at something up close, say a six foot man at 100 yards, it takes a certain angle from his head to his feet. Move him back 100 yards more and he appears smaller, because he takes up less of an angle from head to toe. ("Subtends" less of an angle.)

Suppose you know a man is 6 ft tall. You measure the angle from his head to his toes. Because you're a smart guy, you can use these two facts--his known height and the angle--to determine how far away he is.

There's some basic trig involved. First of all, there's something called "tangent". In a right triangle, that's the ratio of the lengths of the two segments at right angles to each other.

| A
____|
B

In this case, iimagine there's a line from the end of B to the end of A, forming a right triangle. That line is called the "hypotenuse". There's an angle formed between B and the hypoteneuse. Call it "theta", because it's traditional.

What's the angle? Depends on what the lengths of the two legs of the right triangle are. But if you know how long the legs are, there's only one possible angle theta could be. What's more, if you have two triangles that have the same ratio between the legs, the angle theta is always the same.

The greeks noticed this and came up with the idea of "tangent". Tan for theta is in this case A/B.

So we can write the equation TAN(Theta) = A/B

Suppose we know A. In that case we can solve for B, B=A/TAN(Theta).

This is the basics of ranging with a mildot. Think of the A leg as being the height of the target, and the B leg as being the distance to a target. We know A, We know theta, and we can determine TAN(theta). The only unknown is B, the distance to the target, and we can use some basic algebra to determine that.

As it turns out, TAN(1 miliradian) = .001, TAN(2 miliradian) = .002, etc. So, using the formula above, TAN(Theta) = A/B, we can put in names for the values we're dealing with:

Height in miliradians * TAN(.001) = height of target / distance to target

height in milliradians * .001 = height of target / distance to target

distance to target = (height of target * 1000)/ height in milliradians

So suppose we have a 6ft guy. We look at him in the scope and discover he takes up 4 radians of angle.

distance to target = (2 yds * 1000)/4
distance to target = 500 yards

He starts running away. A few seconds later he takes up only 3 miliradians on the scope.

distance to target = (2 yds * 1000) /3
distance to target = 666 yards.






Perfect.
Link Posted: 10/29/2004 10:46:04 PM EDT
Correct mcgredo but don't overwelm the poor guy. Let him grasp the concept first.
Link Posted: 10/29/2004 11:16:54 PM EDT
[Last Edit: 10/29/2004 11:22:16 PM EDT by gaspain]
I made a simplified cheat sheet for range finding. You all are free to use it.

[One "mil" is the space between the dots on the reticle; like counting inch lines on a ruler]

[for larger sizes just multiply the 12" range by however many feet tall the target is.]




Link Posted: 10/29/2004 11:24:27 PM EDT
Very nice chart.
Link Posted: 10/29/2004 11:31:26 PM EDT
Real Mil Dots courtesy the shoot
Link Posted: 10/29/2004 11:59:21 PM EDT
[Last Edit: 10/29/2004 11:59:49 PM EDT by magnum_99]

Originally Posted By RyJones:
Real Mil Dots courtesy the shoot




Glad you pointed out that article (it's my primary reference when I need to refesh on the subject).

It explains where others fail about the differences in the Army mil sytem and the Marine mil system and how each uses a different reticle having different values.

Anyway, mil-ranging is freaking hard and not very accurate for me after about 500 yards. I just cannot seem to get the 10ths right often enough to be real confident with it.

More practice will make it better but I'm thinking that a Leica LRF would do a much better job faster and I could always confirm range/test myself with the mil ranging.


Oh, and a Mil-Dot Master is a must--it's too easy to in the field to screw up with the calculator--though it really helps to get a grasp on the math. I'm no trig expert, but get it well enough to make sport of it at least.

Link Posted: 10/30/2004 2:31:01 AM EDT
[Last Edit: 10/30/2004 2:32:25 AM EDT by Jeep29]
Magnum 99 has a point. I'm a bit on the lazy side and I hate math so I bought one of these. www.mildotmaster.com/
Link Posted: 10/30/2004 3:50:10 AM EDT
tag
Link Posted: 10/30/2004 5:13:39 AM EDT
Tag
Link Posted: 10/30/2004 5:35:11 AM EDT
[Last Edit: 10/30/2004 5:38:55 AM EDT by Warrior-Poet]
Originally Posted By DesertRider:
Okay. Spell it out for those of us who are not familiar with the jargon, or are not mathematically inclined.


First off, subtend simply means to drop incrementally below a given reference point. Yes/no?
So each of the "dots" beneath the center(?) is used to measure what? The height of the object being viewed?
NO. Subtend means that the distance between dots equals 1 milliradian, regardless of range. NOT bulletdrop. At 1000m, 1 mil = 1 meter.


Or are we supposed to estimate the height of the object at a presumed distance and use the dots to estimate the actual distance?
You presume that an erect hominid is ~ 2m tall in gear and hat (Intel will tell you different). By knowing that the hominid 'stands' 2m, that means at 200 meters he'll subtend 10 mils. At 1000m, he'll look really tiny, and subtend 2 mils (three dots, connected). At 500m, he'll stand 4 mils tall, yadayada.

How do you compensate for drop of the projectile?
By knowing how much drop a round has, you can use mils to apply a quick aim-over or aim-off (for windage). Training is the way to develop this skill, and the use of good tools like the MilDot Master.

Blah, blah, blah. I don't even know what fargin questions to ask.

Is there a way to simplify this process so I can understand it without boring myself into a catatonic state?
TRAIN

I've got a couple of mil dot scopes that I've never even used because I haven't bothered to take the time to figger it out.

Someone he'p a challenged brutha out !
GET a MilDOT Master, and about 500 rounds of ammo. Setup targets at different ranges, and TRAIN
Link Posted: 10/30/2004 5:36:30 AM EDT
[Last Edit: 10/30/2004 5:37:21 AM EDT by Warrior-Poet]
*
DELETE
Link Posted: 10/30/2004 5:38:03 AM EDT
Purchase the Mil Dot Master and it will set you free. Dillon Precision sells it. Google for it.

There is also a long range shooting game that is excellent for learning how to range with the Mil Dot scope. IM if you need the name.
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