You’ve just bought your first scope like I did in January 2018 and now you want to put it on a different rifle and avoid stress at the range where minor adjustments on your scope bring about major adjustments on the target.
The answer is simple: reset your scope to factory zero, also known as optically centering your scope.
By following this guide step by step on how to reset a scope to factory zero, you’re going to reduce the time you spend at the range trying to figure out why your shooting is inaccurate and more time shooting with an optically centered gun and having fun with your friends. After you reset just one scope to factory zero, any other scope you want to optically center will be a breeze!
items needed to Reset Your Scope
1) Your scope (my scope is a Nikon Buckmasters II 3-9×40)
2) Screwdriver or Allen wrench depending on your scope
There are two methods to reset a scope to factory zero: the mirror method and the counting method. Although I will explain both, I chose the counting method to reset my personal scope to factory zero because it is more precise and more commonly used to optically center a scope. It will take more time and will require some math—just dividing by 2!—but it’s more systematic. The mirror method requires a mirror and does not work well with scopes that have an illuminated reticle.
Mirror Method Step by Step Instructions
Step 1) Put your scope flush with the mirror.
Look at the crosshairs. If the scope is optically centered, you will just see the reticle. If it is not, you will see a shadow of the reticle in the reflection.
Step 2) Line up the shadow of the reticle with the reticle itself.
To reset to factory zero, you need to line up the shadow of the reticle with the reticle itself. You can do this by adjusting the elevation (top) and windage (side) turrets. There is no particular way to complete this step. It is more trial by fire. Keep adjusting the turrets until the shadow and reticle are lined up.
Counting Method Step by Step Instructions
Step 1) See if the turrets on your scope require an additional tool.
The scope on my .243 rifle uses turrets that are adjustable without the use of any tools. Your scope may require the use of a screwdriver or an Allen wrench to make adjustments.
Step 2) Turn your elevation (top) turret as far as it can spin in one direction.
On my elevation turret, I turned it “up” in a clockwise direction until the turret reached its max movement.
Pro tip: When bottoming out your turret, do not over torque the turret because it could damage the scope. Stop once you feel resistance in the turret. Additionally, your turret may turn counterclockwise. Make sure you just follow the direction of the arrow on the turret.
Step 3) Count the number of clicks when you spin your turret in the opposite direction.
After maxing out my elevation adjustment, I turned it “down” in a counterclockwise direction, counting each click until I had maxed out my elevation adjustment again. When I maxed out my scope, I counted 48 clicks. You likely will have a different number.
Step 4) Divide the number of clicks you counted in half and turn the turret to the divided number.
I divided the number of clicks I counted in half and got 24. I then turn the elevation knob “up” in a clockwise direction, counting the clicks again until I reached that middle number of 24.
Step 5) Repeat this process on the windage (side) turret.
To briefly summarize, turn the windage (side) turret as far as it can go in one direction, stopping when you feel resistance. Count the number of clicks when you spin the windage turret in the opposite direction and divide that number in half. Turn the windage turret to that number.
Commonly Asked Questions
When will I need to reset my scope to factory zero? You might need to reset your scope to factory zero for three reasons: 1) you want to swap scopes between rifles, 2) you bought a used scope and you want to reset it to factory zero, and 3) you want to speed zeroing procedures on a rifle at the range and save ammo. In all three scenarios, resetting your scope to factory zero is an important first step for using a new firearm or a firearm that you haven’t used in a while.
Does it vary substantially from scope to scope? Scopes obviously differ, so the types of tools will you need to reset your particular scope to factory zero may differ from others, but you won’t need anything more than a screwdriver or Allen wrench.
Related: A list of our favorite long range scopes on a budget.
Is it necessary to slip the scales after I reset to factory zero? Yes, you should make use a screwdriver or an Allen wrench to adjust the turret caps (and thus, the adjustment scale) to match the mechanical zero on the scope (see video between 8-9 minute mark). When a scope is optically centered, it allows you to maximize the amount of adjustments you can make on your elevation and windage turrets, thus maximizing how far and how precise you can shoot.
How long does it take to optically center a scope? If you use the mirror method, it could be quite quick. The counting method will take more time, but it shouldn’t take more than a couple minutes.
We hope you enjoyed this tutorial and have used it successfully to reset your scope to factory zero. It’s very important to optically center your scope if you haven’t used it for a while or if you’re borrowing someone’s rifle to ensure that you have a stress-free day at the range.
As you’ve seen in this step by step guide, resetting a scope to factory zero doesn’t need to be confusing. It doesn’t require a lot of tools—at most, all you’ll need is a screwdriver or an Allen wrench—and it’s easy to do once you get the hang of it—the only math you have to do is divide by 2!
So, the next time you want to change your scope to a different rifle, you don’t need to worry because you know how to reset a scope to factory zero.