If you’ve ever looked through a rifle scope, you’ve probably noticed a series of numbers printed on its body. Understanding what do the numbers mean on a rifle scope is the first step to using it effectively and making accurate shots.
These numbers tell you the scope’s magnification power, the size of the objective lens, and other key features. Getting to know them will help you choose the right scope and set it up properly for your shooting needs.
What Do The Numbers Mean On A Rifle Scope
The main numbers on a scope, like “3-9×40,” describe its two most fundamental specs: magnification and objective lens diameter. Let’s break down what each part means.
Magnification (The First Number/s)
The number before the “x” is the magnification. A scope marked “4×32” has a fixed power of 4x. This means the target will appear four times closer than it would with your naked eye.
Scopes with a range, like “3-9×40,” are variable-power scopes. You can adjust the magnification from 3 times up to 9 times closer. This flexibility is useful for different situations.
- Low Magnification (e.g., 1-4x, 3x): Great for close-range, fast shooting. It offers a wide field of view, making it easier to track moving targets.
- Medium Magnification (e.g., 3-9x, 4-12x): The most versatile choice for hunting. You can use low power for woods and higher power for open fields.
- High Magnification (e.g., 6-24x, 10x and above): Designed for long-range precision shooting where seeing tiny details at great distance is critical.
Objective Lens Diameter (The Second Number)
The number after the “x” is the diameter of the objective lens in millimeters. This is the lens at the front of the scope. In a “3-9×40” scope, the objective lens is 40mm wide.
A larger lens gathers more light, which can mean a brighter image, especially in low-light conditions like dawn or dusk. However, a bigger lens also makes the scope heavier and may require higher mounting rings.
Other Important Numbers and Markings
Beyond the basic model numbers, scopes have other important markings that affect your shot.
Reticle Adjustment Numbers (MOA or MRAD)
On the adjustment turrets (the dials on top and side), you’ll see numbers. These indicate how much the point of impact moves per click. The two main systems are:
- MOA (Minute of Angle): Common in the US. 1 MOA is roughly 1 inch at 100 yards. A turret marked “1/4 MOA” moves the impact 1/4 inch at 100 yards per click.
- MRAD (Milliradian): Common in tactical and long-range circles. 1 MRAD is about 3.6 inches at 100 yards. A “0.1 MRAD” turret moves impact 0.36 inches at 100 yards per click.
Field of View (FOV)
Often listed in the manual or on the box, FOV is the width of the area you can see through the scope at a specific distance, usually 100 yards. A wider FOV is helpfull for finding and tracking targets. FOV decreases as you increase magnification.
Eye Relief
This is the distance your eye must be from the rear lens to see the full image. It’s crucial for safety, especially on high-recoil rifles. A scope might have “3.5 inch eye relief” marked. Always ensure your scope is mounted to provide this distance.
How to Choose Based on the Numbers
Picking the right scope depends entirely on what you’ll be using it for. Here’s a simple guide:
- Close-Range Hunting (Under 100 yards): A low-power scope like a 1-4×24 or a fixed 4×32 is ideal. The wide view helps in thick brush.
- General Purpose & Big Game Hunting: A 3-9×40 or 4-12×50 is the most popular and versatile choice for most hunters in mixed terrain.
- Long-Range Target Shooting: Opt for higher magnification, like a 5-25×56 or 6-24×50. Pair this with a scope that has clear, tactile turrets for lots of adjustment.
- Consider the Rifle and Recoil: A heavy-recoiling rifle needs a scope with generous eye relief (like 3.5-4 inches) to prevent it from hitting your eyebrow.
Putting It All Together: A Step-by-Step Example
Let’s say you have a “4-16×44 SF” scope mounted on your rifle. Here’s how you interpret and use it:
- Identify the Numbers: You have a variable power scope. You can zoom from 4x to 16x magnification. The front lens is 44mm across.
- Set Your Magnification: For a medium-range shot at a stationary deer, you might dial up to 10x. For scanning a hillside, dial down to 4x for a wider view.
- Use the Turrets: The top turret adjusts for elevation (up/down). The side turret adjusts for windage (left/right). If it’s a “1/4 MOA” scope, four clicks will move the point of impact 1 inch at 100 yards.
- Check Eye Relief: When you shoulder the rifle, you should see a full, clear picture without any dark shadowy rings. If you don’t, adjust your head position or check the scopes mounting.
Common Mistakes to Avoid
- Too Much Magnification: Higher power isn’t always better. It narrows your field of view, amplifies shaky hands, and can make finding a close target difficult.
- Ignoring Eye Relief: Mounting a scope without ensuring proper eye relief is a common error that leads to poor shooting form and even injury.
- Misunderstanding the Reticle: Some reticles are simple crosshairs, others have marks for holdover. Know which you have and how to use it before you rely on it in the field.
FAQ Section
What does 3 9×40 mean on a scope?
It means the scope has variable magnification from 3x to 9x, and it has a 40mm diameter objective lens. This is a very common configuration for hunting rifles.
What is the best magnification for a rifle scope?
There’s no single “best” magnification. It depends on use. A 3-9x or 4-12x scope is an excellent all-around choice for most hunting situations, balancing power with a good field of view.
Is a 50mm objective lens better than a 40mm?
A 50mm lens can gather more light, potentially offering a slightly brighter image at dawn or dusk. However, it makes the scope heavier and taller. For most daytime hunting, a 40mm or 44mm lens is perfectly sufficient and offers a more compact package.
What does MOA mean on a rifle scope?
MOA stands for Minute of Angle. It’s a unit of measurement for angular adjustment. On a scope turret, a marking like “1/4 MOA” means each click of the dial will move the bullet’s point of impact by 1/4 inch at 100 yards (and 1/2 inch at 200 yards, etc.).
How important is eye relief?
Extremely important. Sufficient eye relief keeps the scope from hitting your face during recoil. It also ensures you can quickly get a full sight picture. Always check the manufacturers specified eye relief distance and mount your scope accordingly.
Understanding the numbers on your rifle scope demystifies its operation and turns it from a mysterious tube into a precise tool. By knowing what magnification you need, what size lens is appropriate, and how to read your adjustment dials, you can make confident, accurate shots. Remember to match the scope’s specifications to your specific rifle and the type of shooting you plan to do most often. With this knowledge, you’re well on your way to better shooting.