How to Get the Most out of your Mil-Dot Reticle
Over the last
couple of years the mil dot reticle has become less of an option
and more the standard in tactical rifle scopes. Since its inception
with the Unertl USMC sniper scope and later in various versions of
the Leupold Mark IV scope, military snipers have come to know the
mil dot reticle as a reliable means of determining distances to
targets, establishing leads for moving targets, and for alternate
aiming points for windage and elevation holds. Military snipers who
are graduates of formal programs of instruction have spent numerous
hours honing their ability to use the mil dot reticle and are
comfortable and competent with it. Military snipers are easy to
train on the mil dot reticle, as the military has been using the
mil relation formula in one form or another for many years. As the
WERM rule (width of correction = Range x mils observed), it has
been the mainstay for determining adjustments when calling and
adjusting indirect fire weapons such as mortars and artillery. On
the other hand, so me Law Enforcement and civilian tactical and
practical long-range precision shooters are a little hesitant
sometimes of the mil dot reticle because of a lack of proper
training. I hope this article will help remedy this problem.
The mil dot reticle is a post and wire
reticle with 10 mils (milliradians) between opposing posts and dots
spaced 1 mil apart on the wires, minus the reticle intersection so
as not to obscure the aiming point. A milliradian is an angular
unit of measure that just happens to equal one yard at 1000 yards
and 1 meter at 1000 meters. Knowing this fact we can, through the
wonders of elementary mathematics, use this little critter to
determine distance to an object when the size of the object is
known. The sniper simply measures his target using the dots, then
works a simple formula to obtain the target's distance or the
distance to an item near the target.
How the milliradian became the unit of measure of choice is
fairly interesting as sniper trivia. Back when the military was
determining how to graduate their artillery pieces the techno-geeks
settled on the milliradian as the unit of measure for their sights.
Since there were 6,283 milliradian (2 PI for all you math whizzes)
in 360 degrees they rounded up to 6400. The Soviets on the other
hand rounded down and ended up with 6200 mils in a circle for their
artillery sights, compasses, etc.
As the Marine Corps sniper program grew and matured during the
late 70's, the snipers desired more accurate range estimation
abilities than what the issue 6x30 and 7x50 binoculars and the 3x9
Redfield scope were allowing. The binoculars had hatch marks that
were graduated in 10 mil increments with the actual hatch mark
lines being 5 mils long (Steiner M22), which were all too coarse
for obtaining much precision. Add to this that the Accu-trac system
in the Redfield, using an 18-inch stadia line intended for deer
hunting, left much to be desired for tactical shooting. We at the
Scout/Sniper Instructor School used a "barber pole" to teach
students to mentally break the reticles of the binoculars into
finer sub-tensions than for what the binoculars were originally
designed. This barber pole had 4" bands painted on it and we set it
out at 111 yards where each band equaled 1 mil. This allowed the
student to see what the graphics on the reticle subtended including
hatch marks, numbers etc. For example, the base of the number 2
equaled a certain fraction of a mil and the tips of the number 3
equaled another number of mils. All of this was fine and dandy but
a better way was needed.
Although the mil dot system is both simple and accurate, as with
anything else it does have limitations, especially if you haven't
received formal training on them. The owner's manuals that usually
come with the civilian scopes are very basic when they explain the
use of the reticle. I've been teaching the use of the things for
over 18 years and have seen most of the problems that students run
into when first encountering mil dot reticles. Even high-tech
devices such as laser range finders have limitations and
disadvantages and low-tech mil dots are no exception. In this
article I will cover some facets of mildot usage that will enhance
your ability to use them.
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 backward 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.
So as you can
see the mil relation formula shouldn't scare anyone off. As a
matter of fact there are ways to make the use of the formula even
easier. Many data books such as the TRGT data book and others have
charts developed using computer spreadsheets that allow the shooter
to find the target size and the mil reading on the chart and it
gives the shooter the distance without any hate or discontent. You
can even make your own using the above formulas if you know how to
use a spreadsheet such as MS Excel.
The EASIEST way to deal with this formula is to get yourself a
The Mil Dot Master. This handy slide-rule type
device does the calculations for the mil relation formula, corrects
for target size when viewed at angles, corrects for slope, gives
MOA/mil/in equivalence and even predicts the future. (You have to
bury some chicken bones and some other stuff to get the last
feature).
Reticle Focus
The first thing we will talk about is reticle focus. In order
for the sniper to obtain precise mil readings the reticle must be
properly focused. If the reticle is out of focus, the reticle will
appear fuzzy and go in and out of focus as the eye attempts to zero
in on it. Not only will mil readings be difficult to obtain but the
sniper will also suffer eye fatigue over long periods behind the
scope as the muscles of the eye attempt to maintain focus. Steps
for focusing a scope's reticle are:
- Look at a distant object (about 300 yards) and allow your eyes
to become focused on it.
- Quickly look through the scope at the sky or a blank wall and
check to see if the reticle is immediately sharp and crisp. If it
is, then no further adjustment is needed.
- If your eye has to re-focus AT ALL on the reticle then
proceed.
- Grasp the eyepiece and back it away from the lock-ring. Turn
the eyepiece several turns so as to move at least 1/8". It will
take this much change to achieve any measurable effect on the
focus. Then repeat step one.
- If the image is better, continue to turn the eyepiece in the
same direction. If it is worse, turn the eyepiece the other way and
repeat the previous steps until the image of the reticle is sharp
and crisp immediately upon looking into the scope.
- Do this several times. Taking the focus past the point of best
focus and back again will help to ensure you have the clearest
setting. Then lock up the eyepiece by screwing the lock-ring back
to the eyepiece.
- Some scopes feature a quick-adjust eyepiece and therefore
simplify this operation.
Target/Objective Focus
One area that is
often overlooked when ranging with mil dots is target focus. If the
target is out of focus it will either read slightly larger or
smaller than it should when properly focused.
There have been many occasions while working as an instructor
where I have found students do worse on ranging with mil dots than
with binoculars or even the naked eye. Most of the time this ceases
to be a problem after they begin ensuring that both the objective
and the reticle are sharply focused.
Ambient Light Conditions
As with all other methods of range estimation that uses the
sniper's eyes, the nature of the ambient light conditions can
affect the sniper's ability to obtain an accurate mil reading.
Effects such as glare, mirage, haze/fog can obscure the target or
alter how the sniper sees the edges of the target which will all
cause inaccurate readings. In order to deal with this, a sniper
must practice obtaining mil readings in all weather conditions and
take notes as to corrections that he must make in those conditions.
For example a sniper knows that in foggy conditions he needs to add
.1 mil to his mil readings or in bright sunny conditions he has to
subtract .1 mil on light colored targets due to glare. So practice
obtaining distances with your scope in all conditions and confirm
distances with a laser range finder. Keep notes as to how different
light conditions alter your mil readings.
Hang on a minute!! Use a laser range finder to confirm
distances? You are probably asking, "Then why the hell worry about
mil dots if I have a laser range finder?" Well, have you ever had
batteries die on you or have a piece of electronics go belly up?
Also, have you heard of laser detectors? Besides, mildot reticles
have other uses besides ranging. OK, now that we've cleared that up
I'll continue.
OK, let's look at what we have up to this point. We've learned
that we have to make sure our reticle and target are in focus. No
problem here as we should have these items under control anyway.
We've had to either learn a simple formula or buy a The Mil Dot
Master. No big deal here either. All we are left with now is to
figure out how to measure objects with the reticle. Let's see if
there are any major obstacles here.
Reading the Dots
The precision
tactical shooter must be able to obtain accurate mil readings to
the tenth of a mil. This is where it is important to know the
sub-tensions on your reticle. For example, I know in my Leupold 3.5
x 10 M3 LR with the USMC stamped wire reticle pattern, the dots
themselves are .25 mils and the posts are 1 mil wide when the scope
is at maximum magnification (more on this in a minute). In Leupold
scopes with round, dot-etched glass reticles the dots are .22 mils
in diameter and the posts are .5 mils wide. This enables me to
break the reticle down as in the illustrations above left.
The importance of being precise on your readings becomes evident
when working at long range. For example, if a 40-inch target (the
size of a kneeling man) is incorrectly measured at 1.5 mils it
would range out to 740 yards where if the correct reading were 1.6
mils it would actually be at 693 yards. Assuming there is 5 MOA
drop with a .308 between 700 and 800 yards you could be dialing on
around 2 MOA too much elevation. At 700 yards that is 14 inches and
may put you over the target depending on your aiming area. So here
are some helpful tips when measuring a target.
- Have a steady rest for your rifle. Just as steady as when you
are firing. Lay the rifle on its side if you have to.
- Use a post for one end of the measuring scale if possible. This
will give you a clear point for one end of your measurement.
- Make sure the target/reticle are focused.
- Practice obtaining mil readings on targets at known distance.
Using the formula given above determine how many mils a target
should read then work on it until you can see that measurement in
the scope.
Variable Power Scopes
My last tip there brings up an interesting point in regards to
variable power scopes with mil dot reticles. Most American variable
power scopes do not magnify the reticle along with the target. In
other words the reticle remains the same size as the target image
zooms. This can wreak havoc if you try to measure a target at the
wrong magnification, as the dots will only equal 1 milliradian at
one magnification setting. Knowing what magnification setting your
scope is set up to use the dots on is CRITICAL to getting accurate
readings. Most scopes are set up to use their highest power setting
and some have an index mark on the power ring. One problem I've
noted with the variable power scopes is that the setting that the
factory tells you to use can often be off a bit. I've had students
be constantly off on readings by 1 or 2 tenths and get flustered as
hell. Some of this can be due to out of focus reticles but many of
them figure out that the index mark is off a hair. By using the
barber pole I mentioned earl lier, you can find the EXACT point
where the mil dots subtend precisely 1 mil. As a side note you can
also find the point where the dots equal 2 mils and other
readings.
Other uses of the Mil Dot Reticle
I think we've pretty much exhausted material on the mil dot
reticle as a ranging tool. I will now go into its other uses in
establishing alternate aiming points for moving targets,
elevation/windage hold-offs and quick follow-up shots. As with any
tool in our toolbox, the more we know about it the better off we
are. If I can use a piece of gear for more than one purpose it
becomes more valuable than a highly specialized piece of gear such
as a laser range finder. (Although lasers make nice paperweights
and Frisbees when their batteries die or the light conditions
render them useless.) These other uses are just as valuable as the
primary range finding purpose of the mil dot reticle.
Leads for Moving Targets
When a shooter is training on moving targets he should be taught
to calculate leads for moving targets knowing the targets speed,
time of flight of the bullet and the targets direction of movement.
The formula is:
Time of flight (sec) x Speed of target (fps) = Lead from
center-mass in feet
(full value lead)
Since it is easiest to establish a lead from a target's leading
edge and we want a lead in mils we will then use the formula:
(Lead in feet x 12) ? 6
(Range x .01) x 3.4
We can now use our mil dot reticle to hold off instead of having
to guess at target widths and other not-so accurate methods. This
formula is a bit ungainly to use in tactical situations, and it
doesn't take into account different shooters' reaction times, but
it should be used in training to determine starting leads when
engaging live fire moving targets. The shooter then fine tunes his
leads and writes them in his data book.
Elevation/Windage Hold-Offs
Mil dot reticles can also be used for alternate aiming points
for elevation and windage holds, as there are often situations
where a sniper may not have time to dial on his elevation and sight
settings. Snipers often have to deal with targets that appear
unexpectedly, multiple targets at different distances, gusting
winds of varying direction and the thing we all don't want to think
about, a miss or an insufficient hit. In these situations the
shooter often doesn't have time to deal with turret caps, 1/4 MOA
target turrets, or in the case of the miss or insufficient hit,
changing the sights. In these occasions, WHEN EXTREME PRECISION IS
NOT A REQUIREMENT, it is better to establish an alternate aiming
point with the mil dot reticle and hit the target.
Windage Hold-Offs
When the USMC Unertl scope first came out in 1981-82, it only
had 4 MOA of windage in each direction. As anyone who has shot past
300 yards knows, that isn't enough windage to handle win drift
caused by your buddy's heavy breathing from the next firing point.
So we had to use the mil dots for windage. This is a simple feat if
you just remember that 1 mil is 3.5 MOA. So if I need 3.5 minutes
of right windage I leave "0" windage on the windage knob and hold 1
mil dot right of center mass. If I need 4 MOA then I hold a tad
more than 1 mil dot. 2 mils? Hey, remember when we broke the mil
dot reticle down for precise measurements when determining
distances? It's the same deal with wind hold-offs. Break the mils
into thirds and you have 1 MOA hold points; OK, so it's 1.13 MOA
hold-offs, big deal.
Elevation Hold-Offs
Now let's talk about elevation hold-offs. In order for us to use
a mil dot reticle for elevation holds we have to determine from
what sight setting we will be holding off from. In most situations
this will mean that we will leave a certain sight setting on the
rifle when not set for a specific target. This is very similar to
the military battle-sight zero concept where an M16A2 is zeroed for
300 meters, which allows the rifleman to engage targets from 0-325
meters by just aiming center mass. In US Army doctrine with the M24
sniper weapon system and M118LR ammunition (175 gr. Sierra BTHP @
2600 fps) the sniper leaves his 500m zero on the scope with zero
windage. Then by using the elevation holds in the chart below, he
can get rounds on target without taking the time to change his
elevation setting. Another use for mil dots is when we have to
engage multiple targets at different distances and we have time to
set it up. We know that if we have to engage a target at 600 yards
then drop down to 300 yards and dr op another one all we have to do
is calculate the elevation difference between 300 and 600 yards
then dial on the elevation for 600 and hold low for the 300 yard
shot. In this case I know that there is 7.5 MOA difference between
the 600 and 300 yard shot. So after engaging the 600 yard target
with my 600 yard sight setting, since it is the more difficult
shot, I will then hold 2 mils under the 300 yard target and engage
it. The .5 MOA error (1.5 inches at 300 yards) in hold is nothing
to worry about in MOST situations.
Follow-up Shots
The last thing I will talk about in regards to the mil dot
reticle is its usefulness when firing rapid follow-up shots when a
quick correction in elevation or windage is required. In these
situations a follow-up shot is needed quickly! If the first shot
was a miss, it won't take the target long to figure out what is
going on. If he is trained or just real smart, as soon as he hears
the crack of the round or some result of its impact he is gonna
move. But in many situations the target won't move due to ambient
noise masking the shot or just plain stupidity as in the case of
the FBI field SWAT snipers that got off 3 shots at a hostage taker
without the perp figuring out what was going on. (In this case the
sniper's shots were hitting a low wall in front of the rifle that
the sniper didn't know was in the way. The third shot hit home
after the sniper raised his position.)
In the case of a well fired shot that missed or was off-center,
the observer can give the sniper an alternate aiming point using
the mil dots as with windage holds. If the shot was at 200 yards
and it was 4 inches (2 MOA) low, the observer tells the sniper to
hold 2/3 mil high and fire again. This is all assuming of course
that the sniper calls the first shot a good shot. If he called the
shot low, then the sniper should fire center again and pay
attention to the fundamentals this time.
And you thought that all mil dots were for was range estimation,
didn't you?
I hope this information has shown you that mil dots are a
valuable aid for the precision tactical shooter/sniper. It may seem
like a lot of information at first but as you absorb this stuff
remember that much of it can be simplified with aids like cheat
sheets, crib notes and through the use of devices like the The Mil
Dot Master even us Neanderthals can handle mil dots. Those that
can't or refuse to use them are missing out on a valuable tool. But
that's OK. Those batteries in that laser are probably OK.
By Kent W. Gooch, CWO2, USMC (ret)
http://www.mil-dot.com/articles/how-to-get-the-most-out-of-your-mil-dot-reticle
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