Instructables

How To Shim A Scope Mount

Picture of How To Shim A Scope Mount
When trying to zero a rifle scope you may run into the issue of barrel droop to the point at which your scope's adjustment is no longer able to compensate. This guide may save you from having to buy an adjustable scope mount.

Barrel drooping is very common in Break Barrel Air rifles.
 
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Step 1: Basics:

Although your scope may point straight off the receiver of your rifle your barrel may not be capable to correct the difference meaning the distance that the scope has to point down for the barrel's trajectory to be parallel with the scopes trajectory.

Step 2: Shimming

Shimming is a way to 'help' the scope point downward without using the scopes internal adjustment capabilities.

A shim is anything that can prop the scope into the position desired.

For this I recommend using card stock, sheet plastic, aluminum sheeting (soda cans) any one of those will work just fine as shim material.

You will need scissors as well to cut the shims.

Step 3: Starting It Off

Begin by removing the scope from the scope rings. Be careful to not drop the optic. Now carefully cut your shimming material into a strip the width of the scope ring base. Then cut the shim to the length at which the strip sits nicely in the "cup" of the lower half of the rear scope ring mount.

Note: each shim will raise the scope a touch to help offset the adjustments on the scope.

Note 2: you may need multiple layers of each shim.

Step 4: Final Steps

Picture of Final Steps
Reattach the scope to the scope ring mounts and pay attention when tightening to make the crosshairs as square as possible again.

Good thing about this is that when done properly it will not damage or require you to modify your scope and can easily be undone.

Good luck!

Feel free to comment any questions.