Mil v MOA. Did I understand it?

P

Pond James Pond

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The first "high-end" scope I bought was my Burris XTR 312.

It was on offer and seemed to be good so I took a rather expensive punt. The Mil-dot version had been sold out by the time I had read up about them and so I got the remaining, slightly cheaper "Plex" reticle.

Now I have MOA 1/4 click turrets, but the Burris came with MRAD sleeves that you can use to replace the MOA graduated sleeves.

I had been toying with the idea of trying MRAD as a ranging method just because it seems simpler to do on the hoof. Right now I am at set ranges: 100m, 300m, but if I ever get my behind into gear and get my hunting permit, I will be in the great unknown!! There it seems that MRAD may have the edge, but here is the chink in the armour as I understand it.

Does using MRA effectively depend on some sort of graduated reticle?
In other words would my fairly featureless duplex reticle make MRAD useless?
 
Is it a plain "plex" reticle or is it their "ballistic plex" with a few dots down the vertical crosswire?
If the ballistic plex, you can use it for ranging and holdover once you have determined the spacing. Either by reference or by field test. It might come out even in mils or minutes, you will just have to find out.

If a plain plex, you can use the distance from the center to where the "plex" increases in width as a ranging feature. Again, you can look it up or gauge it against a known target at a known range. It is unlikely to come out even in mils or minutes, you will just have to do the arithmetic. Or paste a chart on the stock, which is what most shooters I know do.

It is academic to me, I am not a good enough field shooter to try a shot at game beyond the "point blank" range of a typical hunting caliber.
 
Yes, there can be arithmetic involved, even algebra.

I could not find a listing for a Burris XTR with plain plex reticle.
Perhaps you can, with a catalog number off the box.
Perhaps that will lead you to the size of the thin inner plex. If not, you can scale it against objects of known size at a known range.
A 100 meter range makes mils easy; 10 cm at 100 meters subtends one milliradian.
 
It's become a mental math management nightmare. It used to be simple for over 60 years. Then a few ignorant but powerful people in different disciplines got some sight makers to change the angular movements of their aiming axis to something that exactly matched mathematics. Their new hand held calculators solved trigonometry problems whose answers for a minute of angle didn't equal what worked good enough for everyone else.

Didn't matter that target printing company's products never changed their grid sizes. Who puts 100 yard targets with inch spaced grid lines at 95.492967201841884504522543994065.... yards so the lines are spaced exactly 1 minute of angle apart? Same thing with the European metric system of sight adjustments and metric target ranges and scoring ring sizes. Inches per hundred yards or centimeters per hundred meters was easy, simple and manageable by everyone.

Didn't matter that there's four MIL systems on this planet.

Didn't matter that there's not enough matter in the known universe to make enough pencil lead or pen/printer ink and media to write all the numbers down that are an exact amount for it.

Didn't matter that the tolerances in optical lens' focal lengths and adjustment thread counts caused errors in actual line of sight angle changes per adjustment unit to often be bigger than the difference between the methods used.

Simple systems are better.
 
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I could not find a listing for a Burris XTR with plain plex reticle.
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Here's mine for your viewing pleasure!!

One of the 4 thin bars in the middle is about 5-6 inches at roughly 100m! (Based on the drain-pipe coupling on the roof of a house I can see from my window!)

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I have no idea what MOA the thin, central section equates to though.
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On my Leupold VXIII 4.5-14x40 scope, with the adjustment set at 4.5 power, the distance between the intersection of the cross hairs to the point that the duplex hair gets large, is 16 inches at 200 yards. Which happens to be the vertical chest size of an average whitetail deer, or the horizontal chest size of the average human being. At 600 yards the adjustment would be at 14 power. At 100 yards the deer body would fill large post above crosshair intersection to large post below intersection.

Here’s what Leupold says:

To estimate range, follow these steps;

1. Looking through the scope, note that the space between the tip of the thicker post and the center of the reticle covers 16 inches at 200 yards at 4.5 power.

A deer’s body is approximately 16” from top to bottom.

2. If you’re targeting a deer, with a body that is 16” top to bottom, adjust the power selector so that the deer’s body fits between the center of the crosshair and the top of the lower heavy post.

3. Next, read the approximate distance in yards or meters… from a minimum of 200 yards at lower power to a maximum of 600 yards at high power.

My scope is graduated 4.5 to 14 power. Also 200 to 600 yards. Filling the crosshairs as explained above on a whitetail deer you would get the following.

4.5 power = 200 yards
6 power = 300 yards
10 power = 400 yards
12 power = 500 yards
14 power = 600 yards

Is your Burris scope the same? I don’t know you’d have to try it.
 
Didn't matter that there's four MIL systems on this planet.
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There is only ONE definition of a radian, and a milliradian - and it is not a system; and is neither a metric nor an Imperial measurement (feet/inches).

A radian is a geometric description and trigonometric measurement of parts of a circle.

A "Mil" is simply a milliradian or 1/1000 of a radian.

A radian is not a unit of measure in and of itself so neither is a milliradian. Both are an angular expression of part of a circle.

One radian is the angle created at the center of a circle by an arc on the circumference of the circle that is equal in length to the radius of the circle.

It makes a pie wedge shaped section that is approximately 57.3 degrees. So, there are 6.283 radians in a circle - or 6283 milliradians.

The circumference of a circle is 2 x Pi x the radius. So, there are 2Pi Radians in a circle because the length of the radian arc is the same as the radius.

A full circle is 2 x Pi x 1 radian = 360 degrees.

Since a radian is mathematically defined as the angle formed when the length of a circular arc equals the radius of the circle, a trigonometric milliradian (mrad), is the angle formed when the length of a circular arc equals 1/1000 of the radius of the circle.

In order to use a variable power scope with milliradians, the scope needs to have a front focal plan (FFP) reticle with Mil markings so that the distance between the Mil markings stays fixed as the magnification changes.

In inches, 1 Mil = 3.6 inches at 100 yards or 36 inches at 1,000 yards.

Most Mil scope turrets are calibrated so that each click is 0.1 milliradian equaling a change of 0.36 inches at 100 yards or 3.6 inches at 1,000 yards.

The benefit to a Mil / Mil reticle scope is that it can be used for range estimation which, in turn, can be used to estimate bullet drop or windage corrections.

If you have an object in the scope with a size that can be easily estimated - fence post, prairie dog, deer, human, etc. - you use the following calculation to determine distance.

Target size in (yards or meters) x 1000 / MRads (read on reticle)

As an example -

You're looking at a deer and it is 4.0 Mil markings from hoof to shoulder on the scope reticle. You estimate the deer's height to be 50- 54-inches, or approximately 1.5 yards in height.

1.5 x 1000 = 1500 / 4 = 375 yards

Another way to do the problem is to take the known object and divide it by Mils and multiply by 1000.

If you had something that you knew was 2 yards high and it was 4 Mil markings on your scope the problem could be done -

2 (yards) / 4 (mils) = 1/2

1/2 x 1000 = 500

That is the reason some people like Mil /Mil reticles and turrets - it makes distance compensation adjustments more accurate as compared to minute-of-angle adjustments which can only be roughly estimated.
 
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Geometrically true, a milliradian is precisely defined as far as you care to carry out the decimal places of 2000 x Pi.

But there are different MIL systems in use.

Geometrically, there are 6283.185... mils around a circle.
But in military usage, things are simplified.
The Artillery Mil, now NATO Mil, is 6400 to the circle.
The Infantry Mil was 6280 to the circle, close to the geometry, but less convenient subdivisions.
The Russians really simplify at 6000.
The Swedes are going from 6300 to 6400.
I saw one mention that the French infantry insisted on being mathematically correct and used the exact value.
 
"...no idea what MOA the thin..." Equates to nothing. It's an optical thing that draws the eye to the centre.
A 5 or 6 inch drain pipe coupling is enormous as pipes go. That'd be a roof drain pipe. Think door knob size. Suspect you'll find the centre of the reticle covers more like 3ish inches at 100.
A "Mil" is an artillery thing. One mil equals 1/6400th of a circle. You don't care about it anyway. It has nothing to do with Minutes Of Angle.
A Mil/Mil reticle scope is a marketing term that means 'Military'. You don't care about that either.
You only need to worry about where you're reticle is sighted in.
"...A deer’s body is approximately 16” from top to bottom..." More like 18" on full grown deer, but close enough. snicker.
 
There's 5 different mile standards:

Statute mile = 1760 yards.

Nautical mile= 2025 yards +/- a bit depending on source.

US Navy radar mile = 2000 yards.

International survey mile = 1,609.347219 meters.

International metric mile = 1,609.344000
 
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I was in school before 1970 and learned the nautical mile as 6080 feet.
And read sea stories where it became apparent that the guns and torpedoes were trained on a mile of 2000 yards.

At least the French System is more consistent, based on that platinum bar in Paris then, umpty zillion wavelengths of a particular light source now.

I wonder where we would be if the Jefferson decimal system based on the length of a one second rod pendulum (about five English feet, EXACTLY five decimal feet) had taken hold.
 
Thanks for the explanations. Buckhorn's in particular: that makes it much clearer and confirms what I thought: my reticle is probably going to make it difficult to do those sort of calculations.

However, I may well try and work with Mike38's suggested method. That could work. After all the thin sections of the reticle are a constant feature that I can see whilst aiming, so they could be used as a rough benchmark for distance calculations.

Th actual crosshair is very small in terms of what it covers on the target: I don't remember it ever obstructing my view, even when trying to aim at crosses made with marker pens.
 
I have all kinds of scopes with all kinds of systems--and to be honest the older I get the longer takes for me to figure the mumbo jumbo out. : )

My all-time favorite is the SWFA mil-mil system and reticle--not because it necessarily helps me make calculations faster--it's just the general layout makes it more "granular" for longer shots and makes it easier for me to switch between hold-over or clicks on the fly.

 
Buckhorn nailed it. There is only one MilRad, which is one thousand of a Radian.

However different groups use different "numbers" for milrads.

A mil being 6283 in a complete circle, this number is not divisible into fractions for simplicity the Artillery uses 6400 mils, the Infantry used 6280 (the Infantry has since went with the Artillery mil.

Does it really matter: As range increases, so does the error. What is a few yards to a 105 shell, or a 16 inch gun, as the error increases so does the size of the shell who's bursting radius takes care of the error (to a point).

If you are interested in precision rifle shooting to 1000 yards, the correct mil is critical, Not so much if you're shooting a 105 round at 5000 yards.

Using the Artillery mil in rifle shooting would give you an error that decreases (in actual inches) at shorter distances and increases at longer distance.

As said, its math, do you need to be supper accurate, or do you need to be quick.

To make it simpler, lets replace Mils with MOA.

To determine distance the correct formula when using MOA is:

Size of target X 95.5 /MOA.

Lets say you are shooting an 18 inch target wand you have MOA marks on your scope.

18 X 95.5 = 1719. You look in your scope and there is 4 MOA covering the 18 inch target. 1719/4 =429.75 yards

Lets say you left you calculator home, it would be simpler to use 100 instead of 95.5.

So 18 X 100 = 1800. 1800 / 4 = 450/ or a 20.25 yard error.

Using my '06 w/175 gr bullets that would be an error of one MOA in sight corrections or at 450 yards about 4.7 inches. That error (using 100 vs 95.5) decreases at closer distance, and increased at longer distance in actual inches on the target.

At normal hunting distances up to 300 yards your error wouldn't be over 3.14 inches or less. Not a big problem in hunting large game. But if you're banging steel at 1000 yards or more, you're gonna miss.

The biggest problems in using Mils or MOA scopes in estimating distance is, I may look at an 18 inch target and say its 4 mils, you may look at it and say its a 3.75 mils. An error that increases or decreases. Our eyes are different and things change with light conditions.

Shooting is basically a SWAG with the environmental conditions screwing up the calculations.
 
Mr Pond
I find a conventional duplex quite useful for basic hunting range estimation.
I'll get back to that.As has been explained,trying to use Mils and MOA together ,while it can be done,its a bit like using a Celsius Thermometer when measuring Farenheit,or machining metric parts on inch mills and lathes(as most American machinist often do)Its all useful,but it makes the job harder.

OK,how I use my duplex.I do this mostly with a fixed 6X Leupold scope.Its easiest to do at max X on your variable.
Near as I can tell,,my Duplex covers two mils.Tip to tip,7.2 MOA (Close enough,I know aMOA is a little over an inch.but the nitpicking is confusing)
Again,7.2 in at 100 yd duplex.
I like to hunt Pronghorn.A pronghorn will run reasonably close to 14 in,whithers to brisket.

Its pretty easy.If the pronghorn fits my duplex,A 7 in at 100 yds fits a 14 in target,he's 200 yds. If he fits center cross hair to verticle post tip,he is twice that,or 400 yds.
If he is smaller than that,he is over 400,and I need to get closer.

Interpolating from there becomes second nature with practice.

Suppose your reticle is 6 in at 100 yds.If your deer measure 18 in brisket to whithers,and he fits your duplex,he is 300 yds.If the duplex measures 2/3 his body,he is 200 yds. 1/3.100 yds.

No,its not a laser rangefinder.But if you are working within your practicle forgiving trajectory,SOME ranging error is acceptable.Its the gross error,or lack of ranging confidence,that will cause you to make the classis"Looks far,I'll hold a little high"....And blow the backstraps off the critter.
And its good to know where "too far" is.
I don't twist knobs on this scope.I use Kentucky windage.

This is on a .257 AI,I load it rather zippy.I'm at about 5000 ft.the 115 Nosler has a BC about .435,top of my head.

I zero at 300 yds,exactly on center.Amazingly,that puts me about 3 1/2 in high at 100 yds.So that upper hanging duplex tip is good to shoot an egg at 100 yds.
The lower duplex tip ,amazingly,is a hold point for 420 yds if I recall just right.I used my 1903A4 clone last time,I get fuzzy.
It is NOT a sniper rifle,"LONG RANGE" rifle,but out to 400 yds or so its an efficient HUNTING rifle,and that Duplex and I get along fine.
No reaching for a rangefinder,putting it down,picking up the rifle as Mr. Antelope says"Why is that guy moving his hands around?I think my mom is calling me,Bye Bye!"
You can try here:
http://www.burrisoptics.com/reticles/plex
 
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I use a very special system, sometimes called "The Kiss System". Its based on the use of a Bic pen, and a note book called "DOPE". The more you use it, the easier and more accurate it becomes. Log every shot down range, and after awhile it will all come together.
 
Don't forget that all easy ranging with a scope goes out the window if you have a zoom with variable magnification and and second focal plane reticle that stays constant size when changing magnification. Don't know which version your Burris is.
 
Don't forget that all easy ranging with a scope goes out the window if you have a zoom with variable magnification and and second focal plane reticle that stays constant size when changing magnification. Don't know which version your Burris is.
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I used to love being able to hit hard at 1000 yards. As I get older I find hitting a mini ram at 200 yards with the 22 oddly more satisfying.
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Another reason I use the fixed mag SWFA scope (besides that it's insanely cheap for what you get lol)
 
Geometrically, there are 6283.185... mils around a circle.
But in military usage, things are simplified.
The Artillery Mil, now NATO Mil, is 6400 to the circle.
The Infantry Mil was 6280 to the circle, close to the geometry, but less convenient subdivisions.
The Russians really simplify at 6000.
The Swedes are going from 6300 to 6400.
I saw one mention that the French infantry insisted on being mathematically correct and used the exact value.
Click to expand...

What in the wide, wide World of Sports does any of that have to do with using a Mil / Mil scope?

None of that matters unless you're in the artillery, Russian Army, Swedish Army etc.

YOU'RE USING A RIFLE SCOPE not calling in artillery for an army somewhere in the world.

This is a moot point - it doesn't matter - so all of the "different" Mil basis is a canard meant merely to add confusion and not clarifying how a Mil marked scope works.

You never need to divide or multiply anything by the number of Mils in a circle (6283) - all you care about is the Mil dot or Mil markings on the scope's reticle.

Other than Leupold, the rifle scope manufacturers use 6283 as the basis for commercially available MIL/MIL scopes.

All you have to do is use the simple arithmetic calculations I gave previously.

If that is too confusing or difficult - you can get apps for your cell phone that will do the work for you.

If you don't own a cell phone, don't like to do simple math - there is one more option -

The MilDot Master will do the work for you - assuming you are smart enough to understand how to line up two lines on a cardboard slide rule type calculator (if not - you probably shouldn't be using any type of gun).

Don't forget that all easy ranging with a scope goes out the window if you have a zoom with variable magnification and and second focal plane reticle that stays constant size when changing magnification. Don't know which version your Burris is.
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Even a second focal plane reticle scope can be used for range estimation with a Mil markings, as the manufacturer will tell you at what magnification the Mil markings are accurate.

You take your reading at that magnification as directed by the manufacturer, do the range calculation, and then zoom the scope to whatever magnification you need for the shot.

Honestly folks - it's just NOT all that difficult to use a Mil marked scope.

I use a very special system, sometimes called "The Kiss System". Its based on the use of a Bic pen, and a note book called "DOPE". The more you use it, the easier and more accurate it becomes. Log every shot down range, and after awhile it will all come together.
Click to expand...

Amen brother...+1,000. The pen and notebook are invaluable...I use the Moleskine ruled pocket notebooks.
 
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