How to Use MOA Reticle
The trajectory of a spinning bullet isn’t straight. It’s a downward curve (arc) because gravity pulls down the bullet. Wind also swings the bullet sideways. And so, when you shoot, you hit the target at the zero (sight in) distance. But beyond that point-blank (zero) range, you miss. Hence, you need to make corrections for wind and gravity to be on target once more.
There are two ways you can account for drop and sideways swing of a spinning bullet: holding and dialing.
A scope has turrets and reticles. You can use either or both. Hunters and shooters who have experience choose to hold. However, it’s common for arms users to dial the turret to account for drops and hold the barrel using the reticle to account for wind drifts. Experienced gun users hold for both bullet drop (elevation) and wind drifts (windage).
You use reticles to hold the barrel over the scope’s line of sight to compensate for bullet drop. You can also use reticles to aim and shoot “into the wind” so the wind does the work of pushing the bullet toward the target. This method originated from Kentucky.
On the other hand, you can use the turrets. With them, you don’t need to hold over or hold off the barrel manually. All you need to do is to know how much your bullet drops at a certain range and make the turret adjustments per that knowledge.
You can also make adjustments on the turrets to account for the side-to-side swing of the bullet. But turret adjustment is time-consuming.
Both turrets and reticles have ruler-like hash marks but the focus of this article is on how to use MOA reticles. It’s about how to use your scope to hold the barrel over or sideways to move the bullet’s point of impact, whether it be right or left and up or down to account for gravity and wind. In the next article, we’re going to discuss how to use MOA turrets.
To understand how MOA reticle works, we need to first understand what MOA means.
What’s Minute of Angle (MOA)?
One degree has 60 minutes. Hence, one minute is 1/60th of a degree.
But a circle has 360 degrees or (360×60 = 21600 minutes).
One minute is a very small segment of the circle. Shooters and hunters chose to use it because it can be tedious – and even impossible – to use large angles to adjust.
Why?
The margin of bullet drop is already large at small angles. The magnitude of drop and sideway swing of the bullet grows larger with distance.
When you use basic trigonometry to determine by how much the angle: 1 MOA (1/60th of a degree) is subtended by a chord at 100-yards from the center of the circle (your shooting position), you get 1.047-inches.
Hence, at 100-yards from where you shoot, a chord 1.047-inches long subtends an angle of 1/60 degrees at where you shoot. In other words, 1.047-inches subtends 1 MOA at your position from the target 100-yards away.
Thus, 1 MOA = 1.047-inches at 100-yards.
The distance increases but the angle (MOA) remains constant.
And so, at 200 yards, 1 MOA is 2.094”. At 300 yards, it’s 3.141”, and so forth.
MOA Range (yards) Divergence (inches)
1 100 1.047”
1 200 2.094”
1 300 3.141”
1 400 4.188”
1 500 5.235”
1 600 6.282”
1 700 7.329”
1 800 8.376”
1 900 9.423”
1 1000 10.47”
The length of the chord represents the adjustment you need to make to shift the bullet’s point of impact by 1.047-inches at 100-yards. For example, if you shoot and the bullet impacts at 1.047-inches to the left of the target because the wind moved it to the west, then you need to hold the barrel sideways by 1.047-inches (1 MOA). This is “shooting into the wind” or Kentucky Windage Method.
Hence, you place your point of aim at 1 MOA mark on the reticle to correct for the wind. The same principle applies when, let’s say, you shot a bullet and it impacted at 1.047-inches below the target. You need to raise the barrel; hence, place your point of aim at the 1 MOA mark on the vertical to bring the bullet’s point of impact on target at 100-yards. This is applying the Kentucky Windage Method for elevation.
What is MOA Reticle?
A reticle is crosshairs you see on the scope’s screen when you aim at the target. They are crosshairs in the sense that you see a horizontal line and a vertical line ‘crossing’ each other and meeting (or intersecting) in the middle of the scope’s screen.
The rifling community often refers to this intersection as ‘duplex’; hence, duplex reticle. Duplex because two (double) lines intersect at a center. Duplex scopes are popular among hunters who mount AR 15 hunting scopes on their carbine rifles.
You use the vertical line to make holdovers (or raise your barrel over the scope’s line of sight). On the other hand, you use the horizontal line to make holdoffs (shooting into the wind to accommodate the sideway swing of the bullet).
These two lines you see intersecting on the scope’s screen each has subdivisions (or subtensions). These subdivisions (or hash marks) resemble those marks you see on a ruler. It’s only that each subdivision is not in metric or slug units but MOA.
How to Use MOA Reticle
Each subdivision represents MOA adjustment you need to make at the distance (yards) to move the bullet’s point of impact up or down (vertical line) and left or right (horizontal line).
The center represents MOA adjustment you need to make at the zero distance. But you don’t need to make any adjustment at the zeroed distance to shift the bullet’s point of impact.
Let’s say you zeroed your rifle at 200-yards. Hence, you use the center to place your point of aim at the target that occurs at that zero distance. When you shoot, the bullet’s point of impact won’t deviate from the point of aim. You’d get a dead-on accurate shot.
However, you need to make adjustments for distances other than the zero (center). As the distance grows, so is the need to raise the gun (barrel) higher.
But when you raise the gun barrel, you are essentially using the marks that occur below the center (zero). When you use the bottommost mark, you have essentially raised your gun to the furthest distance your rifle and scope setup can shoot.
Let’s say the target occurs at 500-yards. All you need is to raise your gun such that you use the MOA mark for that distance.
MOA reticles, like turrets, come in different calibrations. The most common ones are 1/8 MOA, ¼ MOA, ½ MOA, 1 MOA, 2 MOA, 3 MOA, 6 MOA, and 8 MOA.
Let’s say you have a 1/8 MOA reticle. You’ll see 8 subdivisions on the vertical and horizontal lines to make a full division. A ¼ MOA reticle has 4 subdivisions to make a full division. A 1 MOA reticle has one subdivision to make a full division. And the 8 MOA has 8 divisions to make a full division.
The finer the subdivisions the better the accuracy. Therefore, 1/8 MOA reticles are suitable for long-range shooting while 8 MOA reticles are suitable for short-range shooting.
Verdict
If you zeroed (sighted-in) your rifle at 100-yards, you are sure you are going to hit the target with accuracy at that (point-blank) distance. But beyond your point-blank (zero) range, you’ll miss if you don’t make corrections for gravity and wind drifts. MOA reticles and turrets enable you to make those corrections.
You use reticles to know where to hold the barrel over the scope’s line of sight (or your line of sight if it’s an iron sight) to move the bullet’s point of impact toward the target. Reticle’s ruler-like hash marks each represent MOA adjustments you need to make at a particular distance.
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Well since this article is about MOA reticles/scopes, it would be kind of hard to calculate or discuss mils within the contents of the aforementioned article.
I thought these stadia reticles were for rangefinding against objects of known size first and foremost. Mildot reticles have slightly easier math involved, and there is no reason at all you can’t calculate your holdovers and your leads and your wind drift in mils instead of MOA.