Can somebody explain the Mil-Dot System?


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Pony Express
August 30, 2009, 02:30 PM
Hello everybody,
Everywhere I turn nowadays I see scopes with a mil-dot reticle available. I see little dots on both the horizontal and vertical lines in the scope and it makes me wonder what they heck they mean. are they simply just a different system for range/wind compensation? why are they so different than the typical 100yd, 200yd, 300yd, etc markings on some other expensive scopes, and what makes Mil-Dot so expensive?

Thanks in advance,
DS

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Lightning12
August 30, 2009, 02:58 PM
I can tell you the basics because I was reading up on these scopes myself lately.

Mil is short for miliradian which is a measure of angle. IIRC one mil equals about 3.75 inches at 100 yards. The dots on the reticle are spaced one mil apart at a given magnification on the scope. If you know the approximate size of your target, you can get a quick estimate of the range to the target by seeing how many mils it takes to match the outline of the target when looking thru the scope. Once you know the range, you combine that with the ballistics of your cartridge to get an idea how much to raise or lower your point of aim. They have little slide rules that come with the scope where you can get quick answers to the problem of computing how much holdover to use.

I have not found the mid-dot scopes to be any more expensive than the same scope with a different reticle option.

I just got a Nikon Buckmasters 4.5-14X with a mil-dot reticle. I don't really plan to use the dots because all my shooting is done at 100 yards at the target range. I got it because there is a wider space of very fine crosshairs than you find in the typical duplex reticle, where the narrow crosshair part of the reticle may only extend a very small distance from the intersection of the crosshairs themselves.

jbkebert
August 30, 2009, 03:07 PM
Really depends on the scope. Some mil-dots are designed for ranging 200, 300, 400 ect like burris. Others are used for ranging game or intended target. The ones we used in the military were used for distance estimation mostly. Say you had a truck in your cross hairs. The length of the truck fit between 4 mil dots. You would refer to your dope sheet. A truck being approx 14' in length covering 4 dots would give you a approximate distance of say 750 meters. THe other thing is that most mil-dot scopes the mils are calibrated for a specific power setting. 4 dots at 10x is a far cry diffirent than 4 dots at 4x. I think most scope companies sell them as tacticool crap that most people do not understand how to use. Now there are some like a leupold Boone and Crockett reticle that are set for a given value in windage and elevation. As far as a true mil-dot scope is concerned to get a full use on it you will need to carry a palm pilot or dope sheet 3 pages long to decipher the info.

jobu07
August 30, 2009, 03:25 PM
http://www.mil-dot.com

Check out that website. It will teach you loads about how mil dots work and there's a program on the site that allows you to "train" with a mil dot to learn about hold over and adjusting.

mljdeckard
August 30, 2009, 03:37 PM
It can be spooky. I spent some with some Marine scout Snipers in Africa this summer, and they can freak you out at how well they use the things. They had trainees learning how ti 'mil-out' targets, (find the range by using the mil-reticles) and they were more consistent than a laser range finder.

They taught that if you are a sniper, you have to become an expert on sizes. What is the average height and width of a male torso? If you are looking at more than one guy downrange, is your target bigger or smaller than the others? Rather than guessing the size, it's better to KNOW the size of something in your sight picture. They were running around with their tapes out, measuring random objects. Then they made a discovery. Every civilian passenger vehicle in Iraq uses 14 inch rims. BINGO. Now, if there's a car in the picture, you can get a good range, even if the wheel is turned, because you still know that top to bottom it's.....14 inches.

If you have a reticle measured out in mils, you always use the same round in the same rifle, you have the math at least written in front of you, and you can accurately size the target, do the math, make the adjustment, and send it.

jfdavis58
August 30, 2009, 03:48 PM
Here is a pretty good explanation (there are others in web-space):Mil_Dot_User_Guide (http://www.mil-dot.com/Mil_Dot_User_Guide.htm#Math).

You NEED four things: a good eye for estimating fractional distances between mil-dots, a good memory for the approximate height and width of several common objects, the mathematical formula shown in the guide (take care of matching units-work in yards or work in meters-don't mix) and a drop table for your particular ammunition (you can use the muzzle velocity and a ballistic program or be more empirical and actually shoot the rifle at distances from 50 yards to what every your gun and you can actually perform).

Estimate the distance by finding an object downrange near the target and recalling its size, measuring it with the reticle as 'so many dots' and apply the math formula. Use your drop table to determine a 'hold'; this can be 'applied' by twisting the elevation turret or directly on the target by holding to some number (and fraction) of dots on the reticle.

Wind estimation works partially by experience, part by guesswork and part by the same method above applied horizontally.


The difference between a mil dot scope and a scope with some other form of 'compensation markings' is one of universal versus specific. The mil-dot system is universal except for needing an ammo specific drop table. The compensation type is based on an average ammo concept-the most likely round for the caliber and game taken with that caliber. With a mil-dot precise placement of the shot is possible, with the compensation type some acceptable strike zone is the best one can do.


Most mil-dot scopes are variables. There are two different mil-dot reticle constructions. The less expensive reticle in the normal place must be set to a specific power (or an additional computation must be performed); the more expensive reticle in/on the 'front plane' enlarges or shrinks the reticle as the power is dialed up and down--i.e. no additional magnification computation.



Mil-dot scopes are more expensive because of several factors: higher power, more light gathering ability, target turrets, reticle position and other extras specific to topics like parallax and the ever present novelty cost.



I've used a mil-dot scope for many years, the math is second nature as are 'sizes'. With a well understood gun/ammo and a good drop table, I can put a shot on target about the time a second can get an accurate estimate of range with a laser range finder and speak it out loud. With a bit of practice this is something anyone can do.

sledhead76
August 31, 2009, 07:19 PM
Just wanted to say great question and great answers, the links in the answers are great as well. It was something I've been wondering about myself as I shop for scopes.

Bwana John
August 31, 2009, 07:31 PM
Remember algebra?

Look up "Radians".

The scope is set up so that the distance between 2 "mil-dots" subtends 1/1000th of a radian.

SNEAKY PETE
August 31, 2009, 09:29 PM
old Sneaky Pete here: someone above used the term milradians which is a trigonometric unit of angular measure which is 1000th of a radian( 1 radian=57.3 deg) therefore 1 milradian(1 Mil)=0.0573deg. basically this works with the WORMS formulia they tought me in FO school in the Corps back in the "Stone Age". Width of target(in yards)./.(divided by) Mils X(times)1000=distance to target(in yards) OR Width of target in "(inches)./.(divided by) Mils X(times) 27.78 = distance to target (in yards). NOW you take a "normal" adult male =2yds tall(+/-) & 1/2 yd wide you can range him pretty close enough to hit him or at least make him take cover. Mil dots work!!!!! once you learn how to use them---THE GUNNY SAID SO!!!! Now my advice to you is go to www.mildot.com and buy yourself Mildotmaster with the included manual and read it. Then run the Ballistics for your particular out to the farthest you think you might shoot and then you can range and adjust fire just like us PROs. THANX--SNEAKY

wally
August 31, 2009, 09:59 PM
Remember the milliradian does not depend on the units, it works for inches, meters, or yards, furlongs, whatever.

The key is knowing the target size in the units your drop table is in or doing the math to convert.

1" at a distance of 1000" is 1 mil, that is 1" at 1000/36 = ~27 yards should measure 1 mil. So you can use standard targets at various ranges and practice reading your mils and doing the math without needing long distances.


--wally.

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