Mils vs MOA the Definitive Reason "Why"

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Both Mils and MOA are an Angle. They were intended to operate as angles and while all angles have linear equivalents, when it comes to shooting there is no reason to use the linear value. We have moved beyond needing to figure the straight line distance. They were always meant to work as an Angle, so we need to think in those terms.



This question comes up just about weekly on the forum. Someone reads about people switching to mils or they see something on TV about Marines using Mils and the question is asked: Should I switch to Mils ?

Once that question is launched you get the alphabet of answers. Everyone thinks they have the right reason why you should switch and yes, there are some very valid reasons to move from a mixed system or from MOAs to Mils, but cutting through the noise is not that easy.

There is a lot of misinformation out there, that Mils are metric and you have to start shooting in meters. Or people will say, “but I think in inches” so they feel they have to use MOA. Neither of these are correct, and trust me when I say, 75% of those answering don’t understand what they read to begin with. Some of it is flat out wrong, the rest is really not relevant to shooting. The term, “technically correct” is used a lot.



Both Mils and MOA are an Angle. They were intended to operate as angles and while all angles have linear equivalents, when it comes to shooting there is no reason to use the linear value. We have moved beyond needing to figure the straight line distance. They were always meant to work as an Angle, so we need to think in those terms.

The problem started when we mixed systems back in the 1970s. Once we mixed our systems, married a Mil based reticle to an MOA based turret the training revolved around converting and what each value “Measured” at distance. This was wrong and thankfully we are correcting these mistakes today. The initial converters, our grandfathers of the shooting world didn’t get this one right and for years we suffered the consequences. A lot of the shooting world is incestuous. It’s a constant cycle of repeating the same old thing over and over, even if that information is wrong. A great example is Humidity. Back in the day, all the military manuals said higher humidity slowed the bullet down. It was repeated by people like Maj Plaster because he just copied what the military said and for years people thought, “well it’s humid out, the air feels thick it must be slowing the bullet”. News Flash, Higher Humidity means the air is less dense. The bullet loves high humidity even though humans hate it.

Instructors would immediately start off a precision rifle class and tell you;

• 1 MOA = 1.047” @ 100 yards
• 2.094” @ 200 yards
• 5.235” @ 500 yards
• 8.376 “ @ 800 yards

Who cares, immediately this is confusing, it has a lot of decimal places and lot of odd numbers in there. So the next thing they did was round this to 1” @ 100 yards because someone incorrectly believed the .047 doesn’t matter. They figured 10 x 1.047 is only 10.47” and not too many of them had the ability to shoot a 1/2 MOA at distance. So True MOA quickly became Shooter MOA or SMOA. Today we call that rounded number IPHY for Inches Per Hundred Yards. One big problem is, we sell it as MOA but in reality it is not just .047”, it’s your dope times that number. So if a typical 308 needs 36 MOA to hit the target at 1000 yards, you have to multiple the difference between SMOA and TMOA as 36 x 1.047”. Which is really 37.692. Why is this difference important, well mainly because of ballistic computers. If you tell the computer your scope dials in MOA and it really dials in IPHY you just created an error which will more than likely result in a miss. People wonder all the time why the computer doesn’t match up, here is possibility number 1.

Mils on the other hand were created a long time ago, and while originally not part of the metric standard, it was added to the metric system later. Mils are short for Milliradian, which like a Minute of Angle is simply a way to express the angles in a circle. You will also see companies identify it as MRAD. For our purposes the definition of Milliradians we use is:

An Angle which subtends a length who’s arc is 1/1000 the distance from the vertex.

So what does that mean for us and why can we use it outside of the metric system:

1 Mil = 1/1000th of 3600 inches which is 3.6 inches or 100 yards. We can have 1/1000th the distance of anything really, a mile, a kilometer, it doesn’t matter.

It’s also 10 centimeters at 100 meter, or for us here in the United States, it can be 1 yard at 1000 yards. So as we can see, it’s just a base 10 system that works because of the angle. If you run across an old S&B scope it maybe marked in CM, the turret will say, 1 Klick = 1CM, this is just a Mil based scope. Because 10 Centimeters is 1/1000th of a 100 meters.

Mils happened in the military because of artillery. In WWI they decided that mils were the best way to figure the shot, and shortly after most countries, including the United States adopted the “Military Mil” which is rounded to 6400. This is why mils are included on the lensatic compass, to adjust for artillery. The reticle in your old Steiners are for artillery and are based on 6400 for the mils.

This also creates a bit of confusion. At the time rifle scopes used the mathematically correct 6283 when putting mils into the adjustment. In 1978 when the USMC decided to use mils they too went with 6283. When the Army contracted a scope to be made with mils they defaulted to the military mil which is based off 6400. After all in artillery rounding is not that big of a deal. After realizing this was an error, they corrected the scopes to use 6283. When you read about an Army Mil vs a USMC Mil it has nothing to do with the reticle design, but the fact early scopes from companies like Leupold used 6400 instead of 6283. It’s not the oval dot vs the round dot. Now, there is a lot of debate over which scopes used 6400 and which used 6283, I’ll just say this, the odds are, unless you are using a Leupold M3A or certain March Scopes, chances are it’s 6283. I will tell you this, if you call customer service at any of these companies, very few know the reason or history or even what standard they use. They will just give you a default answer which could be wrong.



Which do I use and Why


This is really the meat and potatoes of the question. Which one is right for you, as they both have pros and cons.


Get a system that matches your reticle to the turrets ! Period end of debate.


If you are shooting most Known Distance Competitions that allow scopes, like F Class. You are better served to use a scope that adjusts in Minutes of Angles. The distance is known, you have no need to range, the targets are calibrated in MOA and you’ll be able to speak to your fellow competitors in a similar language.

If you are shooting BenchRest you can use anything you want it doesn’t really matter. You zero for distance and how you get there is neither here nor there. You can invent your own adjustments and nobody would care. You can get scopes that adjust in 1/8th of an MOA as well you can get Mil based scopes that adjust in .05 Mils. Equally small .36 / 2 = .18”.

If you only shoot by yourself and don’t compete, never venture far from your local range, and it’s just for the entertainment value, you can go in any direction you want. You only have to satisfy your head. For everything else, Mils are a much better choice and here is why.

When it comes to Unknown Distance shooting, Tactical (PRS) Competitions you will be better served using Mils. Most of the guys on the line will be using them and communication is much more streamlined. It’s a base 10, you can run it on the fly as the numbers are smaller and easier. Mils work, and there is a standard across manufacturers, which is really important. The guy with the Horus reticle can communicate with the guys with an MIL-R reticle, which can talk to a guy with an Old School Mil Dot reticle. It’s all the same system.


Remember your dope is your dope, there is no conversion if you match the system.


While you may need 7.5 MOA to hit a 400 yard target, you use 2.2 Mils to hit the same target. You can easily convert your old MOA dope to Mils using 3.43. Yes divide 7.5 MOA by 3.43 and it gives you 2.2 Mils. All those other numbers are wrong for this purpose. The argument that MOA is finer because 1 MOA equals 1.047” and 1 Mils is 3.6 is a red herring. We dial in 10th, so while 1 MOA is smaller, .3 Mils is 1.08”. Nobody is holding that difference. It’s smaller than your bullet. That is what non-shooters say, it’s a finer unit of adjustment.

• .25 MOA = .26”
• .1 Mils = .36”
• .5 MOA = .52”
• .2 Mils = .72”
• .75 MOA = .78”
• 1 MOA = 1.047”
• .3 Mils = 1.08”

They both interchange in a similar manner and nothing wider than the bullet width even if you are shooting a .22.

If you feel you can’t think in Mils because you see things in Inches, I ask you. How many pennies in a dime ? Because a mil based scope is just adjusted in pennies where 1 Mil equals a dime. Base ten units, 10 clicks = 1 Mil. The successful shooter should not be looking at the target in terms of inches anyway, the target doesn’t matter, what you need to hit it does.

Read the reticle and not the linear distance. The Reticle is a calibrated ruler 3 inches in front of your nose. If you read the reticle, you are not “thinking” you are reading. 1 Mils is 1 Mil, just like with a matching system 1 MOA will be 1 MOA.

In terms of shooter / spotter dialog, you should be calling your adjustment to the center of target as:

Left, 1.4 Mils or Left 4.8 MOA. Nothing in either one of those examples has anything to do with target size. Both use the angle, and both can be read by the reticle without any other reference. The distance doesn’t matter, the target doesn’t matter.


Know your system



It’s important you take the time to check. If you don’t know which scope you have, how they are adjusting, either in MOA, IPHY or Mils spend a little time to find out. This is the only time we want to talk in Linear Values. It can help you determine your system. Get out at 100 yards, use a yard stick and measure. You can do it without shooting.

If we know a Mil is 3.6” at 100 yards, the reticle will move 36” over 10 mils. You can bag the rifle in, put the reticle at the top of a yard stick and then dial up 10 Mils. As you dial up the reticle will go down and it should cover 36 inches.

You can do the same thing to check TMOA (True MOA) vs IPHY or Shooter MOA. You know True MOA is 1.047” at 10 MOA it should move 10.50 Inches, if it moves 10” you have a IPHY. This information is worth knowing as scope companies will do what is easier for them, and still advertise it as TMOA. Most TMOA scopes adjust in .26” at a 100 yards to account for the .047 later.


Don’t fall for the myths that are out there.


We want a matching system so at the end of the day it is WYSIWYG, this way we are not using any conversion. If you see it in the reticle, dial it on the turret. If you can dial it on the turret, you can hold it in the reticle.


What you see is what you get works, it allows for rapid corrections and can get you zeroed on paper in 1 shot if you were so inclined.

If you do have a mismatched system, the easy conversion is:

• .25 Mils = 1 MOA
• .5 Mils = 2 MOA
• .75 Mils = 3 MOA
• 1 Mils = 4 MOA

You can use that measure what you see in the reticle and then dial the conversion with the turrets. It’s not precise but will get you a hit. You can just use the reticle and forget the turrets, but this works if you need to dial what you see.


The Math is…


We can go back and look at all the math when it comes to both Mils and MOA. There is a lot and you can get deep into the weeds with it. But why, especially when it comes to shooting. We have no reason to default to linear values. There are some great resources out there where people do get into the details, but I find it just creates problems. We want to eliminate the mindset where the shooter asks themselves, “what is that at 833 yards”, it’s the angle, so use that number. If we read 2 MOA, that is all we need to know, 2, not 2 x 8.3, just 2. The same can be said for mils. 1 Mil is 1 Mils, end of story.

If you’re gonna range with the reticle, there is a formula for that, but I would recommend you don’t use it on the line. Put a cheat sheet together and use that, do not attempt long hand math in the field, or on the firing line. A little prior proper planning goes a long way. If you’re reaching for a calculator or your phone to multiply 27.77 X 12 so you can divide it by .6 you already lost that stage of the match.


This is much easier than it’s sold to the public as. Don’t get sucked into the cycle of misinformation because the guy at your local gun store is trying to sell you a mismatched system or he is explaining to you about Inches and how he thinks. I think he is wrong and can back that up. You can easily go to JBM Online or use your App to give your data in Mils, MOA, IPHY, so there is no reason to feel out of your depth. You put in the exact same information regardless of what you want the program to output your information too. The only extra step is telling it you want the information in, X, Y, or Z units. If you have data for your rifle when you used your old scope, you can convert that same data to the new angle. It’s easy.

I speak a 3 languages quite fluently, but I use Mils, 99% of the time. I can easily translate it to different units, but when I am shooting I only worry about the angle. How much wind am I use, .5 Mils, how far away from the center of the plate is that, .5 Mils … no other definition needed.

Resources:


Mil Dot Website

Mil & MOA

Wiki Mils

There are 2000p milliradians (˜ 6283.185 mrad) in a circle; thus a milliradian is just under 1/6283 of a circle, or ˜ 3.438 minutes of arc. Each of the definitions of the angular mil are similar to that value but are easier to divide into many parts.

• 1/6400 of a circle in NATO countries.
• 1/6283 The “real” trigonometric unit of angular measurement of a circle in use by telescopic sight manufacturers using (stadiametric) range finding in reticles.
• 1/6000 of a circle in the former Soviet Union and Finland (Finland phasing out the standard in favour of the NATO standard).
• 1/6300 of a circle in Sweden. The Swedish term for this is streck, literally “line”. Sweden (and Finland) have not been part of NATO nor the Warsaw Pact. Note however that Sweden has changed its map grid systems and angular measurement to those used by NATO, so the “streck” measurement is obsolete. - Courtesy of Wikipedia