How To Shim A Rifle?

Are you someone who loves to go hunting? If so, you may have had the problem of your rifle not shooting high enough. While there are different permanent solutions for this issue, in an emergency you can try shimming. This is not something that you want to do frequently as it could damage your rifle, but it may help you in a pinch.

So, how does shimming work? In a rifle with open sight, the rear sight has to move with the pallet to make the shot; so if the rifle is shooting too low, you can shim it and make it shoot high. The same thing can be done when the rifle is shooting too high and the shooter wants to hit a lower target.

What is a Shim & What is Shimming?

Technically, the word shim refers to a piece of material that helps some other objects move. Construction workers frequently use shims to balance the structure of the building. They add a small piece (usually wood) and stick it where they observe imbalance. After that, the extra length is cut out. Carpenters use the same technique while doing the framework of furniture. These shims balance things, and the process of adding them is called shimming.

Suggested Material for Shims

The only thing that matters when it comes to making shim is the thickness of the material. Anything from aluminum foil to an aluminum can would work, and many people use plastic water bottles for creating small shims. Some have even used business cards. For precise shims, you can use brass, cold-rolled steel strips, stainless steel, laminated plastic, and much more. Just make sure the material is not thick enough to bend the scope.

How many Shims are Enough?

Normally it is recommended to use only 1 or 2 shims since using more can damage the scope. As it is an emergency solution, using fewer shims makes it time-efficient. Using more than the recommended amount can cause the scope to dent.

The number of shims depends on the thickness of the material you are using. For example, if you are using a plastic bottle for making shims, then one shim is more than enough, while a soda can is thin enough to use two. Any more shims than that can cause permanent damage.

Shimming above the Scope?

It is not a secret that shimming under the scope makes the rifle shoot higher. What if you place a shim above the scope–will it make the rifle to shoot lower? Shimming above the scope of a rifle does not make it shoot lower.

So what do you need to do if you want the rifle to shoot lower? Simply put the shim under the front ring of the scope. This will lift the front part of the scope and update the impact.

Before You Start Shimming

There is something you can try before shimming to solve your problem. Scope rings are not 100 percent precise, and sometimes all you can do is turn the rings or turn the one-piece mount around. You can also change the position of both runs with one and other. However, it is not a foolproof process. Many times the rings are different sizes, which makes it impossible to change the position, but it is better to do this step first. Just swapping the rings can alter the impact point and if it works, then there is no need for shimming at all.

Things You Will Need

These items are recommended to take with you when you go hunting to make shimming easier if you happen to need it.

1. Mounted Rifle Scope

Shimming is not a solution; it is just a quick fix. This means the rifle you are using probably has a scope already mounted on it. If you do not have the scope mounted then you can also use adjustable scope rings. These rings are used for solving temporary elevation alignment issues with the rifle. Some individuals use an elevated mounting base that is specially created for shimming a rifle scope.

2. Material for Making Shims

You can choose any material that is mentioned above so long as the material is thin. Something as thick as a credit card will not bend properly.

3. Scissors

Get a small yet sharp pair of scissors. Anything that can cut your material of choice will work fine.

4. Small Hex Wrench

A small hex wrench can come in handy on many occasions and solve an emergency. It is always a good idea to carry one in your rifle kit.

5. Small Level

This is also a tool that you always need to carry in your rifle kit. A level tool is not only useful within the shimming process, but it can be used to check to see if the shimming you did a week ago is holding up. As the name suggests, a level can tell you if the scope is leveled out not.

How to Shim a Rifle?

Step 1: Prepare the Shim

First of all, select which material you are going to use for your shim. Start cutting the material so that it is small enough to fit in the bottom part of the scope ring, and if you plan on using more than one shim then make each of them smaller.

Step 2: Remove the Scope Ring

With the help of the small hex wrench, unbolt the screws of the scope ring and remove it, keeping the bottom part of the ring attached.

Step 3: Place Shims

This step needs focus. Place the shims in the scope one at a time with the largest one first and then work towards the smaller. Usually, you would only need 2 shims here, but if you think you need more, research how much a shim can alter your shot.

Step 4: Mount the Scope

Gently place the scope on the rifle and check if the placement is right. Now with the help of the hex wrench, screw the bolts carefully to prevent damage to the scope. Now check if the scope is tight enough. Some people do not tighten the bolts because they are afraid of damaging the scope, but this can cause an accident when the rifle recoils when shot.

Step 5: Use the Level

Check to see if the scope is leveled. A common mistake that can happen during shimming is tightening one side of shim more than the other, but a level will help you check if the shims are balanced and scope is leveled.

Step 6: Test Shoot

Now it’s to test shoot and see if you can zero the scope. Do a little test shot, and if the scope is zero then your rifle is ready for hunting. If the results are not satisfactory, then follow the same steps again until you get your desired result.


Hopefully this article has given you the information you need to shim your rifle. Do not forget that this is not a permanent solution, and it could cause damage to your rifle. So, only shim the rifle when it is an emergency.

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