Mounting And Sighting In A Rifle Scope – Updated [2021]

Mounting And Sighting In A Rifle Scope – Updated [2021]

How To Properly Mount and Sight In Your New Rifle Scope

Here we’re going to go over how to mount a new rifle scope. Also, how to sight in a rifle scope.  We are going to cover some different mounts and rings you can choose to mount your scope.  As well as discuss some pros and cons to those mounting systems.  We will also cover bore sighting your rifle, getting it on paper and zeroing it.  Then we will go over what MOA means and how to fine tune your rifle with a 3 shot group.

Mounting Your Rifle Scope

Bases and Rings

There are a wide range of scope bases and rings. When used together, we call these mounting systems.  Most scope bases attach to the top of your rifle on top of the chamber.  They are usually screwed into small pre tapped holes on top of your chamber.  Some come as two different pieces and some come as one solid piece usually referred to as a rail. Some scope rings do not need a base because they attach to a pre-milled dovetail mount on top of the chamber of your rifle.  Not all rifles have this though, so it is important to look at your specific rifle.  Below we go over a few different mounting systems.

Weaver Style Mounting System



The Weaver style mount and base is a metal rail, which screws onto the top of the chamber section of your rifle.  The rail has slots that run perpendicular to the rail that are evenly spaced.  The scope rings then attach to the metal rail which secures the scope to the gun.

  • Pros
    • Strong and Sturdy
    • Rings are usually detachable without removing bases
    • Able to move scope forward or backward to adjust for eye relief
  • Cons
    • Not compatible with other mounting systems including the picatinny system which looks similar

Leupold Mounting Systems



The Leaupold mounting system consists of two metal mounts and two metal rings. Each mount screws into the top of the chamber part of your rifle.  The front ring secures to the mount by turning it sideways and placing it in the mount.  Then you turn it back to lock it in place.  The rear ring is secured with two windage screws.  Now you can place the scope into the rings and level it.

  • Pros
    • High quality
    • Leupold name is synonymous with quality and hunting optics
    • Clean looking without much added hardware
  • Cons
    • Installation takes more time than others
    • Leupold recommends you use a special wrench for installation

Dovetail Mounting Rings



A dovetail rail is a mounting bracket that is usually milled into the top of the chamber part on a rifle.  This is where the top of the metal on the chamber part of the rifle has two groves that run parallel down both sides of it.  This allows you to secure a base to it and then a scope.  It also allows you to secure scope rings directly to the rifle without the use of a base.

  • Pros
    • Very easy to install and take off
    • No rail which means less things to get in the way of loading ammo or ejecting cartridges
    • Not as expensive as other systems
  • Cons
    • Only 6 screws per ring which can make them less durable

Rifle Scope Rings

There are two import things you need to think about when purchasing scope rings for your rifle.  They are the diameter of the rings and the height.  Different brands of rifle scopes can have different diameters.  Scope rings come in 1 inch, 30 mm and 34 mm diameter.  Look on your scope information to find what diameter you need.  Scope height is another important factor. In general, you want the lowest rings possible that still allow you to look through the scope without seeing any obstructions.  This will allow you to rest your cheek on the stock of the rifle as you aim which will help your accuracy. 

Installing Mounts

So you picked out your mounting system for your scope.  Now it’s time to put it all together and get your scope on your rifle.  There are a few things when doing this that are important and you need to keep in mind.  First, each mounting system’s manufacturer will have instructions on how to instal it.   I recommend following them for a variety of reasons.  The biggest being a new scope is a big investment that you want to protect.  Second, the mounts and rings have screws that torque to specific specifications. If you don’t follow their instructions, you risk making your scope inaccurate or damaging it.

Leveling

leveling tool

You need to make sure your rifle is 100% level when mounting your scope.  Once you know your rifle is level, you will also need to make sure your scope is 100% level.  You will most likely need to place your gun in a vice to do this.  There are leveling kits out there made for this specific purpose.  If you don’t want to buy one, you should be able to do the same thing with a small level and a vice.   Once you have the rifle level in the vice, set the scope in the rings.  Then set the level on top of the scope turret that moves the crosshairs right and left.  Then rotate the scope until it is level.  Once the scope is level, tighten the screws according to the manufacturer’s recommendation.

Sighting In Your Rifle

Bore Sighting

Your scope is now mounted on your rifle, but that doesn’t mean that it is going to be accurate.  We now must bore sight it.  To bore sight your rifle, you will need to take it to a range or set up some targets somewhere you can shoot.  A lead sled or a shooting vice will make bore sighting your gun much easier.  To start you will need to set up a paper target 25 yards away from where you plan to shoot.  Put your rifle in the sled or vice and point it at the target.  Then remove the bolt from your rifle.  If you don’t know how to do this, a quick google search or youtube search will show you how.  Once you remove the bolt, look down the bore of the rifle.  The bore is the interior of the rifle barrel.  Move the rifle around until you can see the target through the bore.  Then put the bolt back in the rifle and look through your scope.  Adjust the crosshairs in your scope with the turrets until you are on the center of the target.  Congratulations, your rifle is now bore sighted.  Various companies do make bore sighters different kinds of bore sighters.  Purchasing a bore sighter will save you time but isn’t always necessary.

Getting Your Rifle On Paper

target

If you hear the term, “get your gun on paper” and don’t know what it means, don’t feel bad.  It is gun lingo that means, when you shoot your rifle at 25 yards at a target and hit it, your gun is on paper.  All you have to do is shoot your rifle at that 25 yard target we used to bore sight it with.  When your bullet hits the target, your rifle is now on paper.

Zeroing Your Rifle Scope

Zeroing your rifle might be some more lingo you are unfamiliar with.  All it means is at what distance from the target, do you want to hit exactly where you place the crosshairs. If the thought is going through your head, “but I always want it to hit exactly where the crosshairs are” check out American Rifleman to learn more about bullet trajectory. Now you need to decide what distance to zero your rifle.  The most common distance is probably 100 yards.  You need to think about what your average range of shot is going to be during a hunt and go with that. For example, if you are hunting whitetail deer in the Eastern U.S. in a field, you might not need to worry about shooting over 250 yards.  But if you are hunting mule deer in the mountains, in the western U.S., you might.  So once you have decided the distance you would like to zero your gun at, it’s time to shoot a three shot group.  Most likely your 3 shot group ended up close together.  If they did, we are on the right track.  If not, I would suggest buying a shooting rest to help you stay steady.  You are most likely flinching when you shoot or you aren’t staying steady.

rifle scope reticle

Fine Tuning

MOA and What It Means

The term MOA can be confusing to a lot of people.  The video below is a quick explanation of MOA.  If you are unfamiliar with what MOA means or want a quick refresh, check it out. 



Ok, so as The Daily Shooter described, a lot of rifle scopes will have ¼ MOA per click.  Remember from the video that MOA is 1 inch at 100 yards. All that means is to move the impact point of your bullet 1 inch at 100 yards, you need to twist your turret 4 clicks in the direction you want your bullet to go.  It’s as simple as that.  Now this is most likely why the most common distance to zero your gun is 100 yards.  It requires the least amount of math. 

Three Shot Group

The three shots in your group ended up being within an inch together, that’s good.  Unfortunately, they are pretty far off from the bullseye.  That’s ok, we can fix that.  You will need a target with an 1 inch by 1 inch grid on it.  That way we can tell how many inches your bullet hit left or right and up or down from the bullseye.  Let’s say you were 3 inches below the bullseye and 5 inches to the right.  Now that we know MOA is 1 inch at 100 yards and our scope is ¼ MOA per click we have to do a couple simple calculations.  On your scope turrets you will have one on the side and one on the top.  The one on the side will say something like up and down with a double sided arrow between them.  The one on the top will say something like left and right with a double sided arrow between them.  You always want to move the turret in the direction you want your bullet’s point of impact to be.  In our example, we hit 3 inches below and 5 inches to the right.  So we need to move our point of impact 3 inches up and 5 inches to the left.  So the simple calculations are, 12 (3 inches x 4 clicks/inch) clicks up.  Then 20 (5 inches x 4 clicks/inch) clicks to the left.  Now that’s done, you will need to shoot another three shot group to see where you are hitting the target now.  The process continues until your 3 shot group hits near the center of the target.  If you are finding yourself shooting more than a couple three shot groups.  Give time for your barrel to completely cool down before shooting the next group. This can cause you to shoot off target because your barrel is hot.

We have talked about everything you will need to do to get your brand new scope on your rifle and sight it in. All the steps from choosing the right mount, boresighting, getting it on paper, zeroing it and fine tuning it, all build on each other.  If you skip any of the steps, all the ones after are going to be off.   So make sure you follow step by step.  Happy Shooting!

Karson

Hey I'm Karson. I've been hunting since I was 8 and shed hunting even before that. If you have any questions for me, fill out a form on the contact page, send me an email at karson@huntinggearinsiders.com or leave a comment on the below. Thanks