What the heck is MOA?

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In scope adjustments, you think in one-degree increments, with 360 degrees being in a circle (remember your junior high geometry class?) Now each degree has 60 increments just like the number of minutes on the face of a clock, with each one of those minutes being an angle from the center.

Stay with us here.

Now each of these "minutes of angle" (MOA) is measured at 1.047 inches at 100 yards-- typically just simplified as 1 inch per MOA. This stays constant and the further away you get from the muzzle it picks up another minute every football field. So for example, at 200 yards, you would have two inches in that same 1 minute of angle, and 300 yards you would have three inches for that same one-minute of angle, 400-4, 500-5 and so forth. Remember, the further away from the bore, even though that same 1 MOA stays constant, the angle gets greater by one inch for every 100 yards.

Clear as mud?

Well how you use this tidbit of information is how we adjust your glass in long range shooting. So now at that 500 yard mark, if you fire and hit the target 10 inches low, since you know that 1 MOA at 500 yards is about 5 inches, this means you need to adjust your optics up by 2 MOA (2 MOA x 500 yards= 10 inches). The same math works if you are 7 inches low at 500 yards, you would adjust your optics by 1.4 MOA, which depending on the clicks on your turret for elevation, you may just be able to adjust out to 1.5 which would leave you just a hair high, but still much closer to your aim point than before.
 
In other words, if you have a gun that will shoot a 1 MOA group at 100 yards, at 1000 yards that 1 MOA will translate to about 10 inches (or 10.47 if you are a stickler).

Now, MOA is not a size, it’s an angle from your bore out to the target. The adjustments that you dial in on your elevation turret of your optics or ticks up on your reticle help bring that cross hair up to where the bullet will be ballistically at that range. The trick is to know what your bullet drop is at designated increments. For instance, if you know that the 175-grain Sierra Match Game King that you fire drops 51 inches at 600 yards, and that at that range your 1-inch MOA is exactly 6.282 inches, you need to come up 8.118 MOA (or as close to it as you can get) on your elevation turret to match your cross hairs to where the bullet should hit.

Make sense?

Let us do another example to see if we are all on the same page. Say you have an 850-yard shot you are trying to make and you know your bullet ballistically will drop 70 inches at that distance. What do you adjust your elevation for in MOA? If you said somewhere between 7.75-8 MOA you are correct. Remember, 850 yards at 1 inch MOA is 8.9 inches. By dividing your 70-inch bullet drop by that figure, you have 7.86 MOA rounded to the closest your scope is graduated for.

Once you have the data you can pull from your dope book and make a cheat sheet with your come ups on them. This card can change out as you change loads or platforms and, due to atmospherics is not set in stone, but can give you the “at a glance” info to help dial in your glass.
 
Simple MOA slide-cards like those made by AccuScope for about $15 and smartphone apps can also help you while in the field.

Don’t get this confused with milrads or mildots, which are often encountered on optics made in Europe or those designed for military end-users. It’s largely the same concept but slightly different.