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What Do The Numbers On Rifle Scopes Mean?

What Do The Numbers On Rifle Scopes Mean?

If you're new to rifle scopes, the numbers can seem confusing. Don't worry—this detailed guide will help you grasp the essentials.  
In summary, these numbers represent the magnification, objective lens diameter, and features like AO (adjustable objective) and parallax adjustment, allowing you to understand the scope's capabilities at a glance.  
Let's dive a little deeper into scope magnification and what those numbers mean.

 

The Significance of Magnificatio

The numbers on a rifle scope, such as those in 3-9x40, primarily describe the magnification capabilities.
The first set of numbers indicates the zoom range. For example, 3-9 means you can adjust the scope to make objects appear three to nine times closer.
Variable magnification is useful for adapting to different shooting scenarios.

Fixed magnification in rifle scopes

Of course, some scopes use fixed magnification, meaning the magnification cannot be adjusted. For example, 4x32 has a fixed magnification of 4 times. These scopes are typically compact scopes, designed to be smaller and lighter, specifically for medium to close-range shooting.


Objective Lens Diameter: A Clear Vision

Objective lens size in rifle scopes

The last number in a rifle scope or the number after the "x," such as the 40 in 3-9x40, refers to the objective lens diameter in millimeters.
A larger objective lens allows more light into the scope, providing a brighter image which is ideal in low-light conditions. Typically, a bigger lens improves clarity but also adds weight and bulk to the scope.
Bigger isn't always better—evaluating the intended use of your scope is crucial.


Windage and elevation adjustments (vertical and horizontal adjustments of the reticle) are crucial for zeroing your scope

Windage and elevation adjustment in rifle scopes

When we engage in long-distance shooting, we encounter a problem where the point of impact differs from the point of aim, which is related to zeroing the scope. Taking the two scopes in the picture as examples, each adjustment unit is 1 CLICK, with each adjustment value being a quarter MOA and one-tenth MIL. MOA and MIL are two different angular measurement units, but they function in the same way. Additionally, different brands and models of scopes have different turret designs, such as built-in turrets, external turrets, and lockable exposed turrets, each with its own advantages and disadvantages, allowing for personal preference in selection.


AO adjustment (Adjustable Objective)

AO adjustment in rifle scopes

AO adjustment is a function found on some scopes, used to adjust parallax. Parallax refers to the phenomenon where the reticle (or aiming point) inside the scope changes its relative position to the target when you change your eye position. This function helps improve shooting accuracy. When shooting, you should first be clear about the approximate distance to your target before adjusting the parallax feature.Different scopes have the parallax adjustment function located in various positions; some are at the objective end, while others are at the opposite end of the windage turret.


Diopter adjustment

Diopter adjustment in rifle scopes

Different shooters may have varying vision conditions, including myopia, hyperopia, or astigmatism. Diopter adjustment allows shooters to adjust the scope according to their vision to ensure that the reticle is clearly focused in the field of view without the need for glasses or contact lenses. Diopter adjustment is typically located on the eyepiece of the scope (the end closest to the shooter), and by rotating the adjustment ring on the eyepiece, the focus can be adjusted until the reticle appears sharp and clear in the field of view.

This guide concludes here, and I believe you now have a good understanding of the numbers on your scope. However, having theoretical knowledge alone is not enough to become a qualified shooter. Grab your rifle, practice diligently, and experience the joy that shooting brings!