Tag Archives: moa

Minute of Angle: what is it? and how to use MOA

If you spend any time in the precision rifle shooting world, it won’t be long before someone mentions MOA. We’re going to dive into a full guide on minute of angle.

Introduction
Some people call it weaponized math, which I like. But MOA is a shortened acronym used to describe a Minute Of Angle.

A minute of angle is an angular measurement similar to a degree. We know that there are 360 degrees in a circle, and we can use a compass to pan a certain amount of degrees right or left, just like when you learned orienteering in boy scouts as a kid.

A Minute Of Angle (MOA) is 1/60th of a degree, so it’s just a finer scale of measuring an angle offset. An MOA can be cut up into sixty seconds of angle, but that is getting so fine we probably don’t need to go into it.
As an angular measurement, shooters use the fine-scale to adjust their sights. In the same way pilots use degrees to adjust their flightpath, we use MOA to adjust the flight of our projectiles. I’ve been playing in that realm for a few decades now, so I’ll do my best to explain this dangerous math as best I can.

What Does MOA Mean?
As I mentioned, MOA stands in for the mouthful; Minute Of Angle. There are several other ways that shooters measure shooting corrections and deviations, the more popular being MRAD (abbreviation for Milliradian) and IPHY (Inch Per Hundred Yards). But let’s not muddy the water and stick to our subject, MOA.

MOA and Target Distance
As an angular measurement, the size of a minute of angle gets bigger as it gets farther away from you.

Imagine it like a very long orange traffic cone. When you look through the hole at the small end, it may only be one inch in diameter. But the same cone at the big end, maybe ten or more inches wide, the angle of that increase IS an MOA.

So keeping with our example, if the small end of the cone was two inches in diameter, then to maintain the same angle at the other end, it would have to be twenty inches in diameter.

Back in the old days, before laser rangefinders, people with less hair than me would use these mathematical calculations to estimate distance. If you know an average male is about six feet tall, you can use an MOA scale built into your riflescope reticle to measure how many MOA tall he is and reverse the math to figure out roughly how far away he is.
Once you know your target’s distance, you can use the exact same measuring scale to correct for the drop of your bullet at that distance. Now you might understand why they call it weaponized math.

Accuracy Measurement
MOA is the most common method of measuring or stating the accuracy potential of a rifle. If your rifle shoots five shots at one hundred yards that measure one-inch center to center, then you can call that group a 1 MOA pattern. If your group measures 1.5 inches, you could call it a 1.5 MOA pattern.

As I mentioned before, an MOA is an angular measurement that increases with distance. One MOA at one hundred yards is about an inch, but it measures over ten inches at one thousand yards.
To be precise, one MOA is not one inch. One MOA is actually 1.047 inches at one hundred yards. And 10.47 inches at one thousand yards, but until you are shooting well enough to notice a ½ inch difference in your groups at one thousand yards, you can just work with the inch measurement.

How to Use Minute of Angle While Shooting
As soon as a bullet leaves the muzzle of a rifle, it begins to drop due to gravity and aerodynamic resistance. The further away the bullet travels, the more it drops, which requires corrective action to “hold over” the target high enough to hit it. But how much should I hold over, you might ask?

Long-range rifle scopes have corrective mechanisms to adjust for that drop. It is accomplished by either holding over the target using the same MOA scale you used to measure this guy, or you can use the turret of the scope to dial the corrective angular adjustment. Continue reading here

Riton Optics RTS Mod 5 6-24X50 Riflescope

The optics race is a nonstop fight to get the attention of prospective shooters. It has been exciting if nothing else to watch some of the developments over the past decade or so, particularly from a consumer’s point of view. But have there been any real game changers?

I am always on the lookout for good optics, as I am frequently approached by friends and others looking for good shooting options. And optics is one of those heavily fielded questions.
So when I had the opportunity to try out one of Riton Optics scopes, I jumped at it.

Riton is a fairly new manufacturer, I had hardly noticed them before getting hands on one of their scopes. That scope is the RTS Mod5 6-24X50, it is a first focal plane scope, which is a must for me anymore. It has a traditional configuration with a side focus/parralax adjustment, an illumiated proprietary reticle with the rheostat ontop of the eye box, and a focus ring at the back.

First Focal Plane reticle

The reticle and turrets are both MOA, I’m more of an MRAD fan, but at least they both match. It wasn’t that long ago that many scopes were a hybrid mix of MOA and MRAD, thank goodness those days are gone.
I like the reticle, I found it very useful for measuring corrections and holdovers. Being an FFP reticle was also very handy, avoiding any kind of field math is a plus for my slow processor.

The turrets feature a push pull locking system, to keep them from being turned unintentionally. There are fifteen minutes per revolution of the turret with a total of 70 MOA internal adjustment, that is plenty of adjustment for the kind of shooting I do. I ran the scope on two different rifles, first on my 6.5CM MDR, a bullpup semi auto multicaliber, and then on my brand new 25Creedmoor, a custom built bolt rifle in an impressive new caliber. Both rifles shoot well beyond a kilometer, and the Mod 5 had all the elevation and power I needed for such shots. (Scope was mounted in a 20 MOA cant on both rifles)

While shooting the MDR I became quite familiar with the features of the Riton scope, though it took me a second to revert back to MOA.
Engaging targets as far as twelve hundred yards was no problem with the Mod 5. I am not a large magnification shooter, I usually have about five to ten more X’s than I need, but most of the time I shoot between eight and sixteen power.

I think that is where the Mod 5 shines, as with most scopes, you loose some clarity and brightness at the higher magnification. And in my experience, the lower the price point on the scope, the higher the disparity in sharpness at high magnification.
The Mod 5 was no different, I did find that at twenty four power it was a little difficult to pick out little details out past the grand mark. I solved the problem by backing off to eighteen or twenty power for those long observations. I also wish I’d had a sunshade for it, most of my scopes use one, and it is very apparent when even a little bit of sunlight hits the objective. Luckily, Riton has me covered, and Ive got a shade on the way.

I also ran a test on the click values, they were consistent, but slightly off. Over the course of the forty nine minutes of available elevation from my zero, the click value was on average 0.262 MOA. Again, thats a little off, but it was consistent. The good part was it returned to zero perfectly every time, and no significant reticle wandering or cant.
There was a time that I wouldn’t have trusted a sub 1000$ optic to be precise for repeatable turret travel in serious long range shooting, but technology has caught up it seems. And now scopes like this one are showing that not only can it be done, it can be done well.

The Mod 5 weighs in at thirty ounces, which isn’t necessarily light when compared to it’s competition, but its not particularly heavy either. For my taste, it’ll do just fine. I am used to hauling heavy guns all over these mountains, so switching to something this light was very refreshing.

I ran the Riton pretty hard, up and down, zooming in and out, hiking across mountains and riding up dirt roads in the bed of a truck, semi auto fire,  mounting, re-mounting, etc. No issues with it so far, it keeps right up with me.
All Riton scopes are guaranteed for life, with no hoops to jump, or rules to follow. Thats good to know, becasue we all know about Murphy’s Law.

There was plenty of things to like about the Mod 5. I like the reticle, and the the glass is inline with the price point, the internals appear to be robust and repeatable, with simple turret rezeroing. I will also say this, according to the medical practitioner, my eyes are in pretty good shape. So I tend to second guess my own approval of some optics, mainly because what looks fine to me, is usually pretty crummy when someone with anything less than great vision tries it out. I was happy that the Riton RTS Mod 5 got more than just my own approval. The clarity and quality of the imagery seen through the scope was exactly what I would have expected for a scope in this price range.

If I had to pick out the things I dont like about it, I guess that wouldn’t hurt either;
-MRAD for starters, its not 1987 anymore. I know there are some misguided souls out there still addicted to minutes, but the rest of us have graduated to MRAD. Having both options would greatly improve this scopes desirability to a larger audience.
-Turret rotation graduations, would be very helpful to see what rev your on.
-Parrallax, seemed a little off at times, not bad, but requiring frequent adjustment and checking.
-Magnification ring, the texturing was counterintuitive, making it slightly uncomfortable from the shooting position to zoom in or out. This is a very small gripe, and could simply be preference.

I dont want to sound too hard on this scope, because I actually do like it very much. Hunting season is here, and Junior and I have a date with several deer, and elk. I have all the confidence in this scope to get us on target, whether it be a head shot on a cow elk at four hundrd yards, or a high shoulder shot on a big cross canyon buck at eight hundred and fifty yards.

I look forward to a long future with this scope, and Im sure it wont be long till Riton brings something new. They obviously have the drive, adapting newer and better optics is inevitable. I’ll be waiting to see what that is, and I’ll make sure to have an empty set of rings available until it does.

-CBM