How to Shim a Scope for Windage

How to Shim a Scope for Windage

Have you ever missed a shot while hunting or shooting due to windage? It can be frustrating, especially when you have put in a lot of time and effort into preparing for that moment. Fortunately, there is a solution that can help you improve your accuracy- shimming your scope for windage.

Shimming a scope is a technique used to adjust the angle of the scope’s reticle, allowing you to compensate for wind drift. It’s a simple yet effective method that can make a significant difference in your shooting accuracy.

In this article, we will discuss the step-by-step process of shimming a scope for windage. We will cover everything from the tools you need to the actual process of shimming your scope. Whether you’re a seasoned shooter or a beginner, this guide will help you improve your accuracy and hit your targets with ease. So, let’s get started!

What is Windage

Before we delve into shimming a scope for windage, it’s essential to understand what windage is and why it matters. Windage refers to the horizontal offset that the bullet will experience due to wind. Even a small breeze can push your bullet off course, causing you to miss your target. Windage affects the point of impact on the horizontal axis (right and left) as opposed to elevation (up and down).

Why Shim a Scope

Shimming a scope is a process of adjusting the height of the rear scope mount to compensate for windage errors. This is necessary because windage errors can result in shots that are not accurately placed on the target. By shimming your scope, you can achieve optimal performance and accuracy from your rifle, even when faced with difficult windage conditions.

How to Shim a Scope for Windage
How to Shim a Scope for Windage

Preparing Your Rifle and Scope

Before you begin adjusting your scope for windage, you need to do a few things to prepare your rifle and scope:

  • Make sure your rifle is unloaded and pointed in a safe direction.
  • Ensure that your scope mount screws are tight.
  • Make sure that your rifle is properly cleaned and lubricated.
  • Adjust your scope to its lowest magnification.

Finding a Suitable Location

It’s important to find a location with minimal wind interference when doing windage adjustments. If there are trees or tall structures, they will block the wind in some areas, and you won’t be able to get a clear reading on the wind’s direction and velocity. Try to find a location that is open and exposed to the elements.

Identifying The Direction And Velocity Of The Wind

Before you start shimming your scope, you need to identify the wind’s direction and velocity. The most effective way to do so is by using a wind gauge, a device that measures the speed and direction of wind precisely. If you don’t have a wind gauge, you can use the following methods to get an idea of the wind’s direction and velocity:

  • Look at the flags in the area. A flag that stands out horizontally indicates a strong wind, while a flag waving gently indicates a light wind.
  • You can throw some grass or dust into the air to see the wind’s direction.
  • Check the weather forecast before going out to shoot to determine how strong the wind should be.

Zeroing Your Scope

Before you start shimming your scope, you should ensure that the scope is zeroed. Zeroing means adjusting the scope’s elevation and windage turrets, so the point of aim (POA) is the same as the point of impact (POI). To make these adjustments, you can use the testing procedure for the particular scope you have.

How to Shim a Scope for Windage

Follow the easy steps below to correctly shim a scope for windage adjustments:

Determine Amount of Shimming Required

Use a boresighter or a laser bore sight to determine how many shims the scope requires for proper alignment. Without shims, adjust the windage and elevation turrets as much as possible in both directions. Then, find the midpoint between these two extremes to establish the original position of the scope in the rings. Measure the distance that you will need to move the scope, divide it by 2, and that’s the number of shims you’ll need.

Purchase Shims

Purchase the appropriate shims for your scope and weight requirements. Steel, aluminum, or plastic shims are available in various thicknesses and are an easy and effective way to correct any misalignment issues. In general, a good starting point is to use 0.005 inch shims and then adjust accordingly.

Install Shims

Once you have the right number and thickness of shims, it’s time to install them. Install them between the rifle and scope rings to ensure proper alignment. Loosen the screws on the scope rings using the appropriate size screwdriver. Insert the shims on one side of the scope mount and tighten the screws to lock them in place. Repeat the process for the other side and ensure that the shims are tightly secured.

Remount Scope and Test Fire

After installing the shims, re-mount the scope to the rifle, and ensure that the crosshairs are horizontally centered. Re-sight the rifle and use the windage turret to make the necessary adjustments. Test your rifle before going to the shooting range to ensure it is functioning properly.

Testing Your Shim

Once you’ve shimmed your scope, you need to test it to make sure it’s working as intended. With the gun set up on a stable rest, aim the crosshairs at the center of the target and take a shot. If the bullet impact on the target is too far left, you need to add more shims on the left side of the rear mount. Conversely, if the bullet impact is too far right, add more shims on the right side.

After each adjustment, test the rifle again, until you have a shot group that consistently hits the bullseye. This method makes sure that the windage is adjusted correctly, and the shooter’s POA corresponds precisely to the POI.

Final Adjustments

Once you’ve determined the correct shim for your scope, you should make permanent adjustments. Remove the scope and mount and apply a small amount of thread locker on each screw. Retighten all the screws and then remount the scope on the rifle. Finally, retest your rifle to ensure it’s still zeroed accurately.

How to Shim a Scope for Windage
How to Shim a Scope for Windage

Tips for Successful Shimming

  • Always use the same thickness shim on both sides to maintain the scope parallel to the rifle.
  • Use a quality set of shims that are made for shim stock changes.
  • Do not over-tighten screws, as this can damage the scope or the rifle receiver.
  • Make small adjustments when zeroing to achieve the best accuracy possible.
  • Be consistent in your approach and keep a record of your shimming.


Shimmying a rifle scope is not a complicated process, but it requires careful consideration to get it correctly done. An adjustment to windage may vary depending on many situations, including the rifle, ammunition, optics, and wind conditions, but this guide will give you an excellent starting point. By taking your time and regularly practicing, you can advance and improve the accuracy of your shots significantly.

Frequently Asked Questions (FAQs)

What are scope shims, and how do they work?

Scope shims are thin metal, plastic, or paper strips that change the height of your scope by adding or reducing space between the riflescope rings and the rifle. Shims are used to accurately align the scope if there are height differences between the mounting rings or to correct misalignments to ensure accuracy.

What tools are needed to shim a scope?

The tools required to shim a scope include a screwdriver, shims, and a wind gauge.

Is it necessary to use the same number and thickness of shims on both sides?

It is recommended to use the same number and thickness of shims on both sides to ensure that the scope remains leveled. However, sometimes this may require a slight deviation to ensure proper alignment.

Can I use other materials besides metal shims?

Yes, but the shim material should be durable, sturdy, and not compressible. How do I know if I’ve shimmed my scope correctly?

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