So you’ve got the new gun, you picked out an optic for your needs, and you’re all ready to go to the range. One problem though:
You’re new to PRS, you don’t know how to adjust a rifle scope, and you’re not exactly a fan of broadcasting that to all your friends.
We’ve all been there at some point. So don’t worry, Blue Line Optics has your back.
In this article we’re going to go in depth and walk through exactly how to adjust a rifle scope. We’ll take into account whether you’re using Mil or MOA, the drop of your bullet, windage adjustment (I know, scary right?) and really anything else you might need.
We made a video about it too, which you can check below if you like that better.
Without further adieu, let’s begin!
The basics to adjusting a rifle scope come from the basics of bullet trajectory. If you didn’t already know, bullets do not fly in a straight path. They fly in a curve.
So when you shoot a gun, you technically need to point the barrel upwards, which is what a rifle scope helps you do.
A rifle scope will help you adjust your line of site so that when your reticle is pointed where you want to hit, your barrel is pointed in a direction so that it will hit that spot.
The scope does this through the use of turrets, called the elevation and windage adjustment turrets. Depending on what measurement your scope is in (refer to your owners manual. It’s not as common now, but some scopes will have markings in Mil, but turrets adjust in MOA. I don’t recommend using this), these turrets will adjust via MOA increments or Mil increments.
Usually but not always a Mil turret will adjust as 1/10 Mil per click, and an MOA turret will adjust as ¼ MOA per click. Click is pretty much what it alludes to – when you move the turret it makes a click.
As you are observing the reticle (like in the picture below) that click will move the reticle either 1/10 Mil or ¼ MOA in the direction opposite of what you tell the turret to adjust for.
For example, let’s say you determine your shot is 1 Mil too low, and you need to move it up one mill. So on the elevation turret tells you to twist in a counterclockwise rotation 10 clicks to move up one Mil.
If you look carefully though, the reticle moves down 1 MIl. Don’t worry, there isn’t anything wrong with your scope, this is what’s supposed to happen.
Let me explain:
You are adjusting your shot to hit higher on the target, because when you shot the first time you determined it was a little too low (1 Mil to be exact).
Well, what do you need to do to hit higher? Move the barrel up.
So the reticle is going to come down so that it forces you to move the barrel up to match the reticle to the spot on the target you want to hit.
The same is true for the windage adjustment. Adjusting left moves the reticle right. Adjusting right moves the reticle left.
This can be confusing at first, but you get used to it the more you do it.
So now that we have that down, how do we know how much we need to adjust in the first place? And how does this differ between Mil and MOA?
We address that next.
We were talking about Mil & MOA and if you are uninitiated in these arts, you’re might be confused. No worries, it’s actually a pretty simple concept.
Mil stands for Milliradians and MOA stands for Minutes Of Angle. Without going into too much detail as we covered in this post I’m going to walk you through the differences.
Mils and MOA are just the way we measure distances when using scopes. They are units of angular measurement which is necessary because when we move a rifle barrel, we don’t move it in a straight linear direction. Rather it moves in an arc.
Since it moves in an arc, we have to use angles to calculate the linear distance it moves. This distance is a function of the distance the target is away from you.
Why? See the picture below. The arc causes the distance between the two lines to increase the farther you get from the beginning of the two lines.
A greater angle corresponds to a greater change in distance, which increases the farther out you go.
Calculating Mil & MOA
There are a couple of basic guidelines for calculating these measurements:
1 Mil is 1/1000th of any distance
1 MOA is approximately 1 inch at 100 yards. I say approximate because it’s actually 1.047 inches at 100 yards. Read our article “what is MOA?” for more details on that.
So at 1000 yards, 1 Mil is? right , 1 yard. How much is 1 MOA? Approximately 10 inches.
On the reticle (like the one to the right) the has marks will be broken down by Mils and MOA. When adjusting your shot, you’ll use these to tell by how much you need to adjust your shot.
I.e. if your shot is 2 MOA to the left to what you need it to be, then you will need to adjust your windage turret 8 clicks to the right. Your reticle will move left 2 MOA, and you’ll adjust it so it’s pointing straight onto the target, thus moving it to the right 2 MOA.
If you get stuck on the Mil and MOA calculation, use this calculator to figure out what your Mil and MOA is at any distance, in inches, yards, meters and centimeters.
For basic reference, 1 Mil is 3.439 MOA. So to find how many Mils are in a given MOA, you just divide the MOA you have by 3.439 and you arrive at the number of Mils. To find the MOA you have based on Mils, you do the opposite.
This is where knowing Mil and MOA adjustments start coming in handy. As mentioned above, your bullet drops the moment it leaves the barrel.
You adjust your scope to account for this. What we do is we use a tool like this ballistic calculator to calculate what your bullet drop is going to be at any given distance.
It’s pretty easy to use. If you go to the link above, you’ll come to the following screen:
You just need to enter in your bullet information here.
Now, keep in mind, you want to be using your own DOPE (Data On Previous Engagements) book and taking your own data. Using a Chronograph helps you calculate your actual muzzle velocity when the bullet leaves your barrel.
This matters because no two rifles, bullets, scopes or shooters are the same. Standardized data often leaves out little nuances that make your situation unique.
So it’s important to keep your own DOPE and to track this over time.
That being said, if you’re just starting out, use the data about your ammo the manufacturer provides. Usually this is on the website, or on the back of the ammo box.
Now that you have this data, use it to enter in the ballistics calculator. Let’s use my Winchester .308 Win Power Points from above as an example:
Note: I got the Ballistics Coefficient from the website since it wasn’t provided on the box
The results will look similar to below:
This is good because now we can use a rangefinder (like this one) to get distance to target. Once we know distance to target, we reference the table to see what the bullet drop is in inches.
Now we can do the math. Let’s do the 500 yard example to start.
We see that the bullet drop is 69.5361 inches. Well let’s say your scope is in Mil.
1 Mil at 500 yards = 500 yards / 1000 = 0.5 yards. 0.5 yards * 3 (feet in a yard) * 12 (inches in a foot) is 18.
So 1 Mil at this distance is 18 inches. Sweet.
Now let’s figure our adjustments. Bullet drop is 69.5361 inches. 69.5361 / 18 = 3.863 Mils. So you will need to drop your reticle by 3.863 Mils.
Now, we can’t make that fine of an adjustment, so we will need to round to the nearest 10th, making this 3.9 Mils.
Remember, our turrets adjust in 1/10th Mil per click. So on your elevation adjustment, you dial up 39 clicks, which comes out to be 3.9 Mils.
Your scope will come down 3.9 Mils, so you’ll make your barrel adjustment so that the reticle lands on the target where you want it.
And that’s it! It really is that easy.
Now we come to wind. Wind can be incredibly complicated, and there have been entire books written on the matter.
That being said, we can get the basics down.
The first thing with windage is to figure out how the wind is blowing. And by how I mean in what direction, and how quick.
A simple way to do this is to check the wind effect on the range you’re one. For example:
- Seeing smoke drift – 0-3 MPH
- Prominent on the face – 3-5 MPH
- Leaves moving – 5-8 MPH
- Leaves and dust blowing – 8-12 MPH
- Small trees moving – 12-15 MPH
You’ll also need to estimate for the direction of the wind. In short you can use the clock system, which basically says winds from 1, 5, 7 and 11 o’clock are given ½ value. Winds from the 2-4 o’clock on the right and 8-10 o’clock on the left are given full value.
Now there are formulas we can use which use these ½ and full values to calculate the shift in direction of the bullet. That being said we can also just use a more complex calculator like the one at shooterscalculator.com.
When you fill out the data you get something similar to what I got here:
This lets you know that at 500 yards, your windage shift is 2.85 inches for a 3 mph wind at 45 degrees (approximately a ½ value).
So if you have a wind coming in from the right, you’ll need to compensate your shot to the right 2.85 inches for the wind.
For a Mil calculation, we know that at 500 yards, 1 Mil = 18 inches. 2.85 / 18 = 0.15 Mils. So we adjust to the right either 1 or 2 clicks to compensate.
Now that’s a very basic example for wind. It gets more complicated when you have multiple winds at multiple directions. But this is a “how to adjust a rifle scope” article, so it will suffice for now.
For those of you that have purchased an FFP scope with a more complicated reticle, like the one below:
You have the option of using a holdover.
For scopes like this, the distances between the hash marks will stay constant no matter the magnification you have the scope set on.
The bottom of the scope has these extra lines with extra hash marks. This gives some reticles a “Christmas Tree” appearance. So we end up calling these reticles “Christmas Tree Reticles.”
What’s great about a Christmas Tree Reticle is that it negates the necessity to make the turret adjustments if you don’t want to make them. You can just use this as a “holdover” meaning holding that part of the reticle over the target.
So using the example we have already above, instead of adjusting the turrets, we can simply move the reticle up 3.9 Mils and to the right 0.1 or 0.2 and align the reticle like below:
This saves you a bunch of time, as you’re not constantly adjusting for things.
There is more that goes into how to adjust a rifle scope than what we have covered, but this was a good first start in learning the art.
It can be confusing at first, but practice over the long term will make a lot of these things second nature.
Drop a comment below and let me know what you thought – do you prefer Mil or MOA? Do you use Holdovers for corrections? What’s your favorite way to tell the wind?
Also leave questions if you got em, I’ll be glad to help!