Spend enough time in the firearms blogosphere and you’ll surely be subjected to heated debates about the costs and benefits of “MOA” versus “MRad” rifle scopes. If you’ve wished the authors of those articles would take two steps back and relax a minute for goodness’ sake, you’ve come to the right place.
First, the basics.
Rifle scopes use MOA or MRad to delineate how much a scope’s point of aim has “moved.” That’s why you’ll often hear long-range shooters talk about moving their reticles “4 MOA up and 0.5 MOA left” or “4 mils up and 0.5 mils right.”
You can do this either by adjusting the turrets on your scope or by using the hash marks on your scope’s reticle. In either case, your scope will be set up in either MOA or MRad, which is why it’s good to understand these terms before purchasing a scope.
You can calculate these adjustments based on a simple equation:
● **1 MOA** moves the point of aim **1.047** **inches** at **100 yards** and an additional 1.047 inches for every 100 yards after that. ● **1 MRad** moves the point of aim **3.6 inches** at **100 yards** and an additional 3.6 inches for every 100 yards after that.
Note: Illustration not to scale.
One MOA or one MRad covers a greater distance as the target moves farther and farther away. At 200 yards, one MOA equals 2.1 inches. At 1,000 yards, it equals 10.5 inches. Same story for one MRad: 200 yards equals 7.2 inches, 1,000 yards equals 36 inches, etc.
(You can get into the weeds about exactly how each measurement relates to a 360-degree circle, but this article is going to stay out of those weeds.)
We can take this equation to calculate how much a scope’s reticle must move to adjust the bullet’s point of impact at a particular distance.
For example, if you’re sighting in a scope at 200 yards, and your shot hits 3 inches to the right of the bullseye, you would do the following calculation: divide the desired point-of-impact shift by the number of inches one MOA or one MRad covers at that distance.
● 3-inch point-of-impact shift = 3 (POI in inches) / (1.047x2 (distance/100)) = 1.4 MOA ● 3-inch point-of-impact shift = 3 / (3.6x2) = 0.4 MRads
Here’s another example you might encounter in the field. If an animal is 378 yards away, and you know your bullet drops 8 inches at that distance, you need to move your point of impact “up” 8 inches. Here’s that calculation:
● 8-inch point-of-impact shift = 8 / (1.047x3.78) = 2 MOA ● 8-inch point-of-impact shift = 8 / (3.6x3.78) = 0.6 MRads
Some MOA scopes adjust in 0.5 or 0.125 MOA increments, but your scope’s turrets probably adjust in either 0.25 MOA or 0.1 MRad. So, in the above example, you’d rotate your top turret eight clicks “up” for MOA or six clicks “up” for MRad.
You can see why long-range hunters and competitive shooters make such a big deal about a bullet’s “ballistic coefficient” or “BC.” A bullet with a high BC slices through the air more effectively, which means it’ll drop less and be less affected by wind. Less bullet drop means less dialing and a greater margin for error if your calculations are off.
It’s useful to understand these concepts and be able to do the calculations by hand, but there are a wide variety of ballistic calculator apps that can do the math for you. KAC Bullet Flight M, Applied Ballistics, and Shooter are three of the most popular, but they all come with a download fee. If you’d rather not spend money, Federal Premium Ammunition also offers their app for free.
Companies such as Kestrel sell rangefinders that solve ballistic calculations, but to really cut down your legwork, you can’t beat the Fury HD 5000 AB binos from Vortex. This is basically like having a little NASA scientist strapped to your chest (that’s a weird image, but we’re sticking with it). The Fury HD has a built-in rangefinder and ballistics calculator, so it can tell you how far away a target is and how much you need to dial to hit it.
You wouldn’t measure a person’s weight in milligrams, and you wouldn’t measure the distance to Phoenix in inches. Like other units of measurement, MOA and MRad are both better in some circumstances and worse in others.
Ryan Muckenhirn is a sales and technical specialist for Vortex Optics. Based on his experience, MRad is usually the better option for long-range hunting and competitive shooting.
“If the choice was available, I’m going to select MRad,” Muckenhirn said. “MRad is a little more intuitive and easier to use.”
Two factors contribute to this ease of use, Muckenhirn said: smaller numbers and easy-to-find subtensions (a.k.a., reticle hash marks).
Smaller numbers are easier to digest than larger numbers. On Vortex’s HSR-5i reticle, for example, the MRad version includes vertical subtensions from 0 to 10 in .5 MRad increments. The MOA reticle, on the other hand, goes from 0 to 32 in 2-MOA increments. If you’re targeting an animal from 400 yards, dialing or holding to 3.5 is easier and more intuitive than dialing or holding to 19.5, Muckenhirn argued.
“We’re looking at smaller numbers on the whole, so a shooter is going to have a more intuitive time using an MRad system over an MOA,” he said.
In addition, it’s easier to see invisible subtensions in the reticle. If you want to hold over to 5.75 MOA in the reticle below, you’ll have to estimate the location of 5 MOA and then further estimate the location of 5.75 MOA. In the MRad reticle, finding 5.75 MRad is much easier and more precise.
If you plan to dial your adjustments using your scope’s turret, you’re more likely to be able to dial precisely with an MRad scope. At 600 yards, a 6.5 Creedmoor drops 11.82 MOA or 3.4 MRads. If your scope dials in 0.25-MOA increments, you’ll have to pick between 11.75 and 12 MOA. But you’ll be able to dial to exactly 3.4 MRads on a scope that uses 0.1-MRad increments.
Still, you might not want to discount MOA entirely. It has its advantages, too. One-quarter MOA equals about 0.25 inches at 100 yards, while 0.1 MRad equals about 0.36 inches. This allows for more precise adjustments using MOA, which is a great benefit for benchrest shooters.
Muckenhirn also pointed out that scope companies like Vortex offer most of their hunting scopes using MOA reticles. This works just fine if you don’t plan to adjust your scope or calculate ultra-precise holdovers. Most hunters simply assign distances to each vertical subtension, which can accommodate most hunting scenarios.
Finally, Americans are used to thinking in inches, and MOA naturally aligns with that proclivity. Most Americans know that a good group at 100 yards is sub-MOA, or under 1 inch. This makes it easier to remember that one MOA covers an additional inch for every 100 yards. While this is less helpful if you’re shooting at 587 yards, for example, hunters are understandably more accustomed to thinking in MOA than MRad.
For the majority of shots in the field, both MOA and MRad will allow you to adjust your scope to make a clean, ethical kill. But you won’t have much success if you spend all your time reading articles like this one and no time at the range. My best advice? Pick one and get to work.