[model99er]

Links on MIL-Dot Scope usage ...

http://www.eabco.com...MildotRep01.htm

http://www.excalibur...es/mil-dot.html

http://www2.leupold....tion_Manual.pdf

Please feel free to add additional / better ones.


99er

[deadeyerik]

Thanx 99er. Don't have time right now but I'm very interested in these.

[model99er]

Your welcome Rik, I'm quite interested in as well. I will prolly still be a "clicker" yet this hunting season, but hope to be a "dotter" come next year.

In my limited reading so far, I found out how little I actually know about proper MIL-Dot usage.

Meybe someone here will speak up and splain it in a way my "pea brain" will better understand.


Here is what I'm having some heart burn with:

For instance, lets say ...
1. I'm shooting a 243 with 95gr BT ammo
2. my zero is at 150yd
3. at 500 yds I'd be ~46in low

The way I'm reading and understanding the links ...
1. if my scope was set to 10 power, one mil-dot increment would equate to 18in. at 500yds
2. but since my scope is set to 20 power, that one mil-dot increment now would equate to 36in. at 500yds
3. so rather than raising the scope by say ~2 1/2 mil-dot increments, I since my scope is set to 20 power I would only need to raise the scope by ~1 1/4 mil-dot imcrements.

Am I understanding this correctly ???


99er

[DJnRF]

Understanding the "Mil-Dot" can be a complex undertaking, but very
useful once you understand. I have given a rather technical method
to explain it here, but it covers all you need, and then some. It does
explain how it differs from the MOA method.

First off ......
The "Mil" in "Mil-Dot" does not stand for "Military"; it stands for "milliradian."
The radian is a unitless measure which is equivalent, in use, to degrees.
It tells you how far around a circle you have gone. 2 PI radians = 360 degrees.
Using 3.14 as the value of PI, 6.28 radians take you all the way around a circle.
Using a cartesian coordinate system, you can use "x"- and "y"-values to define
any point on the plane. Radians are used in a coordinate system called "polar
coordinates." A point on the plane is defined, in the polar coordinate system,
using the radian and the radius. The radian defines the amount of rotation and
the radius gives the distance from the origin (in a negative or positive direction).

ANYWAY, the radian is another measurement of rotation (the degree/minute/
second-system being the first). This is the system used in the mil-dot reticle.
We use the same equation that we used before, but, instead of your calculator
being in "degree" mode, switch it to "radian" mode. One milliradian = 1/1000
(.001) radians. So, type .001 into your calculator and hit the "tangent" button.
Then multiply this by "distance to the target."

Finally, multiply this by 36 to get inches subtended at the given distance. With the
calculator in "radian" mode, type: tangent(.001)*100*36 = 3.6000012"
So, one milliradian is just over 3.6 inches at 100 yards. If we extrapolate, two
milliradians equal about 6 feet at one-thousand yards. You'll see the importance
of this, shortly.

The mil-dot reticle was designed around the measurement unit of the milliradian.
The dots, themselves, were designed with this in mind and the spacing of the dots
was also based upon the milliradian. This allows the shooter to calculate the distance
to an object of known height or width. Height of the target in yards divided by the
height of the target in milliradians multiplied by 1000 equals the distance to the target
in yards. For example, take a 6-foot-tall man (2 yards). Let's say that the top of his
head lines up with one dot and his feet line up four dots down. So: (2/4)*1000 = 500
yards away. This same technique can be used to estimate lead on a moving target
or to compensate for deflection on a windy day.

The distance from the center of one dot to the center of the next dot is 1 milliradian.
We are told (by Leupold) that the length of a dot is 1/4 milliradian or 3/4 MOA (Given
this much information, one can deter-mine that the distance between dots is 3/4
milliradian.). I use the term "length" because the mil-dot is not round. It is oblong.
The "dots" on the vertical crosshair run oblong in the vertical direction. The dots on the
horizontal crosshair run oblong in the horizontal direction. The width of each dot
is an arbitrary distance and is not used for any practical purpose. Like a duplex reticle,
the mil-dot reticle is thicker towards the edges and uses thin lines in the middle where
the dots are located and the crosshairs cross. The distance between the opposite thick
portions is 10 milliradians.

NOTE: 1/4 milliradian = .9" and 3/4 MOA = .785", so, obviously, a mil-dot cannot be
both 1/4 milliradian and 3/4 MOA. I called Premier Reticles (they make Leupold's
mil-dot reticles) and got an explanation: the dots on their mil-dot reticles are 1/4 mil.
They are not 3/4 MOA. Apparently, they (Leupold?) just figured that more shooters
understand MOA than milliradians, so they just gave a figure (in MOA) that was close,
but not super precise. You can contact Premier Reticles via e-mail and request
literature or ask questions.

So, to use a mil-dot reticle effectively, all one need remember is that the distance
between dot centers is 36" at 1000 yards. This lets you determine the range of a
target of known size. At that point, you can dial the scope in for proper elevation
OR use the dots to hold over the proper amount. The dots on the horizontal crosshair
can be used to lead a target (if you know the range to the target, then you'll know
the distance between dots, and thus the distance to lead) or to compensate for deflection.

I hope this wasn't too complex.

[model99er]

DJnRF, on Sep 20 2009, 01:50 AM, said:

So, to use a mil-dot reticle effectively, all one need remember is that the distance
between dot centers is 36" at 1000 yards. This lets you determine the range of a
target of known size. At that point, you can dial the scope in for proper elevation
OR use the dots to hold over the proper amount. The dots on the horizontal crosshair
can be used to lead a target (if you know the range to the target, then you'll know
the distance between dots, and thus the distance to lead) or to compensate for deflection.

I hope this wasn't too complex.

DJnRF,

This ...

"So, to use a mil-dot reticle effectively, all one need remember is that the distance
between dot centers is 36" at 1000 yards."

... is what I had originally understood; which would make that distance between dots 18" at 500 yards.


All was well in my mind until I read this quote from the first link I provided above ...

"The distance between mil dots is 3.6 MOA at 10X magnification, right? That means it's 3.6 inches at 100 yards, 7.2 inches at 200 yards, and about 12 inches at 300 yards. That actually conforms pretty closely to some standard bullet trajectories ( 6.5mm BRM for example)... BUT, you can change the MOA between dots by changing the magnification (some scopes go higher than 10X). If you reduce the magnification the distance spanned between two dots increases. If you increase the magnification, the distance spanned between two dots decreases."

... now if you tell me they are flat-assed wrong in that link about scope power changing the distance between mil-dots, then I'll be as happy as a pig in shit again !!


So, my very basic question is ... does a scope's maginification (power) setting affect mil-dot spacing ??


thanks !!


99er

[deadeyerik]

My brain hurts. I have a range finder. I know the distance. If I change the power do I use a different dot to aim with?

[DJnRF]

model99er, on Sep 20 2009, 02:38 AM, said:

DJnRF,

This ...

"So, to use a mil-dot reticle effectively, all one need remember is that the distance
between dot centers is 36" at 1000 yards."

... is what I had originally understood; which would make that distance between dots 18" at 500 yards.


All was well in my mind until I read this quote from the first link I provided above ...

"The distance between mil dots is 3.6 MOA at 10X magnification, right? That means it's 3.6 inches at 100 yards, 7.2 inches at 200 yards, and about 12 inches at 300 yards. That actually conforms pretty closely to some standard bullet trajectories ( 6.5mm BRM for example)... BUT, you can change the MOA between dots by changing the magnification (some scopes go higher than 10X). If you reduce the magnification the distance spanned between two dots increases. If you increase the magnification, the distance spanned between two dots decreases."

... now if you tell me they are flat-assed wrong in that link about scope power changing the distance between mil-dots, then I'll be as happy as a pig in shit again !!


So, my very basic question is ... does a scope's maginification (power) setting affect mil-dot spacing ??


thanks !!


99er

Oops! Sorry about that. I didn't see where you had questioned the
use of a 20X magnification. Ok. Here we go. The military never
considered the use of scopes over 10X. Even this power tends to
be a hazard to the shooter in not being able to see other targets,
but is assumed that the average soldier would not be using a scope
over about 2X. The 10X used for many years, especially from the
inception of snipers, was primarily intended for ranges of about
500 yards. It was only in later years that higher power scopes
were adopted, and since the Mil-Dot system had been in use by
then for many years, it was continued without change.
The Mil-Dot system is still based upon a 10X scope even though
the civilian market started building scopes of higher power.

However, there are some answers to cope with this. I have
started digging out my old books, so I hope I can give you
what you need to start to figure the calculations you would
need.

Firstly, after reading your first link I notice that it states much
of what I had given. However, it also mentions what is needed
with a higher power scope. Look to the last sentence of the
quote you posted in this message: "If you reduce the
magnification the distance spanned between two dots increases.
If you increase the magnification, the distance spanned between
two dots decreases."
This gives you the answer to your question. Now comes the
'how to' of getting the accuracy you need.

The very first thing you need to know is that it is presumed
by almost everyone that almost everyone understands the
MOA system better than the Mil-Dot system. Thus, it is used
to compare with the Mil system. Specifically, as used by
Leupold, they state that 1 Mil is equal to 3/4 inch MOA. This
is close, but inaccurate. At distance, this can throw you
off. I haven't yet found the right book, but I seem to think
that the real comparison would be closer to .7 inches rather
than .75 inches.

Now, for some formulas. I am quoting from one of my books
in which a USMC, WO2 had written what he was teaching on
this. I have a document file on this, but not yet sure if I can
get the whole document pasted into this.

"The Mil relation formula. There are a couple of permutations
of the mil relation formula floating around. At first look most
of them strike fear in the hearts of most of us Neanderthal,
knuckle dragger types, but they are really quite user friendly.
Granted the formulas require you to use more than your fingers
and toes, but we Marines can handle it! Well, here we go. The
basic one is:

Height of item in yards (meters) x 1000/Mils read = Distance
to item in yards (meters)

This formula is good when the sniper knows an item’s size in
yards. My only problem with this version is that cops often have
to deal with small items such as vehicle wheels, small stickers on
windows, headlights etc. This requires the officer to convert a 7"
headlight into a decimal equivalent in yards before they can work
the formula. And since most cops are fellow Neanderthals and are
usually under a fair amount of stress to begin with, I prefer to teach
the formula:

Height of item in inches x 27.8 (25.4)/Mils read = Distance to target
in yards (meters).

The formula can be worked backwards in training so that if the
distance to the target is known we will know what the mil reading
should be. This is handy for beginners learning to read mil dots. The
formula for this is:

Size of item in inches x 27.8 (25.4)/Distance in yards (meters) = Mils

Knowing the sizes of items being measured is a matter of knowing
your prospective area of operation and making a list of the sizes of
standard items. Make sure you get both height and width of objects
as you can mil both dimensions but the largest dimension mathematically
will usually give the most accurate answer. Military snipers should have
sizes of enemy vehicles, enemy weapons, average heights of soldiers, etc.
An LE sniper should have sizes of traffic signs, bricks, license plates, etc.
So carry a tape measure and a notebook with you and prepare to have
people look at you funny as you measure curbs, traffic lights, mailboxes
and other commonly found objects in your area of operation."

Now, I know that your intended targets are game, and not cars, or
people, so to use an average height of the types of targets you will
usually be sighting would be a good start.

Now, also comes the real problem of figuring out your scope at different
powers. The system developed for the USMC was to use a type of
'barber pole' set out at a distance of 111 yards with bands of 4 inches.
I suspect this would be impractical for you to do, though. That only
leaves two other methods. First would be a lot of practice with a
target of known height at the distance, and power you would use
for this practice. A good common ground would be 500 yards.
Another way would be to get a Mil-Dot calculator. You can find a
number of these at many places that sell scopes. They are a good
investment to be able to figure out your requirements for your use.

I found the website for the one invented and taught by the marine
that wrote what I have.

http://www.snipercou...ildotMaster.asp

I haven't compared this original to others being sold by other places.

I hope this clears up things a bit.

[DJnRF]

I tried to put the whole article on here, but it just
won't put in the diagrams that go with it. The
document file is nine pages in length, but I
could send it via an email attachment if you
like. Just let me know.

[model99er]

deadeyerik, on 20 September 2009 - 10:42 AM, said:

My brain hurts. I have a range finder. I know the distance. If I change the power do I use a different dot to aim with?

Rik,

The way I'm understanding it so far, YES !!
Course the only thang I'm sure of at the moment, is I'm still gunna be a "clicker" this year !!


99er

[model99er]

DJnRF, on 21 September 2009 - 01:26 AM, said:

I tried to put the whole article on here, but it just
won't put in the diagrams that go with it. The
document file is nine pages in length, but I
could send it via an email attachment if you
like. Just let me know.

DJnRF,

Thanks for the help so far.

Yes, please email me the entire article when you get a chance.
Send to ... model99er@yahoo.com

Perhaps I can somehow get it uploaded to here for the others to view as well.

Also, that "Mil-Dot Calculator" looks interesting; I just wish it went beyond the 10x Scope Power.


thanks !!


99er

[model99er]

The attached Word Document ...
"How to Get the Most out of your Mil Dot Reticle, By Kent W. Gooch, CWO2, USMC"
... was kindly provided by DJnRF.

Thanks DJnRF !!


99er

Attached File(s)

•  How to Get the Most out of your Mil Dot Reticle.doc (96.5K)
  Number of downloads: 3

[model99er]

Welp, for wut's it worth, here is my current .243 "cheat sheet" ...

Trajectory for 243 m99 Fed 95gr BT 150yd zero at 3025ft/sec
Ballistic Coefficients of: 0.378
Velocity Boundaries (Feet per Second) of: 3025
............................................................ **Approximate **
Yards... Ft/Sec... Ft/Lbs... In. ....MoA...10X<mildot>20X
0 ....... 3025.0 .. 1929.9 .. -1.5 ....0.0
50 ..... 2897.5 .. 1770.6 .. 0.07 ....0.1
100 .... 2773.6 .. 1622.4 .. 0.60 ....0.6
150 .... 2653.1 .. 1484.6 .. 0.00 ....0.0
175 .... 2594.1 .. 1419.2 ..-0.76 ...-0.4
200 .... 2535.9 .. 1356.3 ..-1.83 ...-0.9 ..0.25 ...... 0.12
225 .... 2478.3 .. 1295.4 ..-3.25 ...-1.4
250 .... 2421.5 .. 1236.7 ..-5.02 ...-1.9 ..0.50 ...... 0.25
275 .... 2365.5 .. 1180.1 ..-7.16 ...-2.5
300 .... 2310.2 .. 1125.6 ..-9.69 ...-3.1
325 .... 2255.6 .. 1073.0 ..-12.62 ..-3.7 ..1.00 ...... 0.50
350 .... 2201.7 .. 1022.3 ..-15.99 ..-4.4
375 .... 2148.5 .. 973.5 ...-19.8 ...-5.0 ..1.5- ...... 0.75-
400 .... 2096.0 .. 926.6 ...-24.08 ..-5.7 ..1.5+ ...... 0.75+
425 .... 2044.3 .. 881.4 ...-28.85 ..-6.5
450 .... 1993.4 .. 838.1 ...-34.15 ..-7.2 ..2.0 ....... 1.0
475 .... 1943.2 .. 796.4 ...-39.99 ..-8.0
500 .... 1893.8 .. 756.5 ...-46.41 ..-8.9 ..2.5 ....... 1.25



99er

[DJnRF]

Well, now you are taxing my old brain. Somehow
something doesn't look right from the 10X to the
20X calculations. I don't know how fast I can
work these out to be sure with what all I have
to do into the next week, but I'll see what I
can do to be sure.

It has been many years since I have had to use
this method myself, and never had to go over the
10X calculations. Where I used to be pretty good
at doing them in my head, that was all before
my brain dried out, and shriveled up so bad. But,
I will take a look at them and try to verify what
you have figured, or if there is a mistake, where
it might have been made. All it takes is time. Of
course, at my age I can't be too sure how much of
that I may have left.

The fastest way would be to use your calculations,
and actually fire with each, the 10X, and the 20X
at the same 500 yards, then check the drop according
to your calculations. I don't have a .243, let
alone one that I know to be accurate enough, but I
sure wish I did.


Dave.

[model99er]

DJ,

Thanks, but take your time.

So far I haven't had a need to use it this year and doubt I will till next year. At the moment, I'v grown rather fond of my current location, which is "mid-field" and my max shot from it would only be around 300yds max.

Next year I'm planning on moving on up to the "point" some, which will allow me to see another different "bottom" field too; my max then will streach out to around 500 to 600yds. I'll also be using my 270 mostly then as well; the Groundhogs in the "bottom" field will give me plenty of pre-season practice with it and my 243's.



You can be damn sure of one other thing, this was the 1st and last time I'll ever attempt to post any column data like that; a royal pain in the ass to get all of the friggin columns alligned. Next time, I'll convert my Excel file to a PDF file and upload the damn thing !!! LOL


99er

[DJnRF]

model99er, on 25 November 2009 - 04:42 AM, said:

You can be damn sure of one other thing, this was the 1st and last time I'll ever attempt to post any column data like that; a royal pain in the ass to get all of the friggin columns alligned. Next time, I'll convert my Excel file to a PDF file and upload the damn thing !!! LOL
99er

Well now, This is one part I can answer real easy. To align the
columns to get it right all you need to do is to start your
message, put down the first line of data, then hit the Preview
button. You then look at how it would appear in the post, and
make any adjustments to correct any noticed problems. In the
preview part you can then just use your 'Enter' key (Return key
on an electric typewriter)and insert each succeeding line of
your data. When you have it all down go ahead and post it. Any
needed changes then would be simple with the Edit button. As
long as you make each data line separate by the Enter key, all
you would need to do is to align each succeeding line with the
line above as you type it. It can really go faster than to use
the method you mention.

I find these forum layouts easier to use than MS Word, or even
my publishing program as I don't have to make separate fields,
or columns, and only have to do the task once. They will
automatically fall into line as long as you get the first one
right, and do each next line right under the one above.
All A Columns..........B Columns..............Group
A1.....A2.....A3........B1.....B2.....B3..........Xray
1A.....2A.....3A........1B.....2B.....3B..........Zebra

Once you get your second line in alignment, just keep typing the
data you want to input, one line under the one above. Just
remember to preview the first, and second lines to be sure they
come out right.

Dave.