If you’re new to riflescopes, the numbers and markings can look like a secret code. Understanding what does the numbers mean on a rifle scope is the first step to using it effectively. This guide will break down all those figures so you can choose the right scope and use it with confidence.
Every scope has a series of numbers like 3-9×40 or 4-16×50 SF. These aren’t random. They tell you the scope’s magnification power, the size of the objective lens, and other key features. Knowing this lets you match the scope to your shooting needs, whether for hunting, target shooting, or tactical use.
What Does The Numbers Mean On A Rifle Scope
Let’s start with the most common format you’ll see: something like “3-9×40.” This is the core specification of the scope. It’s usually engraved on the tube or printed on the box. The numbers are always presented in the same order, and each part has a specific meaning.
The First Number(s): Magnification
The number(s) before the “x” refer to the magnification or power. A scope with “3-9x” means it’s a variable-power scope. It can adjust from 3 times magnification (3x) up to 9 times magnification (9x). At 3x, the target will appear three times closer than it does with your naked eye. At 9x, it appears nine times closer.
- Fixed Power: A scope marked as “4×32” has a fixed magnification of 4x. It doesn’t zoom in or out.
- Variable Power: A scope marked “4-12×44” is variable. You can adjust it anywhere between 4x and 12x.
The “x” and The Second Number: Objective Lens Diameter
The “x” simply means “by” or “times.” The number immediately after the “x” is the diameter of the objective lens in millimeters. In a “3-9×40” scope, the objective lens is 40mm wide. This is the lens at the front of the scope, farthest from your eye.
- A larger objective lens (like 50mm) gathers more light. This can provide a brighter image in low-light conditions, such as dawn or dusk.
- A smaller objective lens (like 28mm) keeps the scope lighter and more compact. It may sit lower on the rifle.
Other Common Markings and Abbreviations
Scopes often have extra letters and numbers. Here’s what they typically mean:
- SF: Stands for Side Focus. It means the parallax adjustment knob is on the side of the scope, not on the objective bell.
- AO: Stands for Adjustable Objective. This means the parallax adjustment is on the objective lens housing at the front of the scope.
- FFP or SFP: FFP (First Focal Plane) means the reticle grows and shrinks with magnification. SFP (Second Focal Plane) means the reticle size stays constant.
- MOA or MRAD: These indicate the unit of measurement for the windage and elevation adjustments. They tell you how much the point of impact moves per click of the turret.
Understanding the Turret Numbers
The dials on top and side of the scope are called turrets. They adjust the point of impact. The top turret is for elevation (up/down), and the side turret is for windage (left/right). The numbers on them indicate how much they move the bullet’s impact.
- Each click of the turret moves the point of impact a specific amount, usually noted on the cap (e.g., 1/4 MOA).
- If your scope says “1/4 MOA,” one click will move the bullet’s point of impact by 1/4 Minute of Angle at 100 yards.
- To adjust for a target at 200 yards, you need to understand that the effect per click doubles at 200 yards compared to 100 yards.
Putting It All Together: Reading a Scope Model
Let’s decode a complex example: “4-16×50 SF FFP MRAD.”
- 4-16x: Variable magnification from 4x to 16x.
- 50: A 50mm diameter objective lens for good light gathering.
- SF: Side Focus parallax adjustment.
- FFP: First Focal Plane reticle (scales with zoom).
- MRAD: Turrets adjust in Milliradian units.
This scope is suited for long-range precision shooting where holdovers and adjustments are critical.
How to Choose Based on the Numbers
Your intended use dictates which numbers are most important. Here’s a simple guide:
For General Hunting (Whitetail, etc.):
A 3-9×40 or 4-12×44 is an excellent, versatile choice. The lower magnification (3x or 4x) is good for quick shots in thick brush. The higher end (9x or 12x) is sufficient for shots across a field or clearing.
For Long-Range Target Shooting:
Look for higher magnification, like 6-24×50 or similar. An FFP reticle and exposed tactical turrets (MOA or MRAD) are very helpful for making repeatable adjustments at different distances.
For Rimfire or Close-Range Use:
A fixed 4x or a low-power variable like 1-4×24 or 2-7×32 is perfect. These scopes offer a wide field of view for fast acquisition on small game or for plinking.
Common Mistakes to Avoid
When looking at scope numbers, a few pitfalls can trip up new shooters.
- Over-magnifying: More power isn’t always better. High magnification narrows your field of view, magnifies shake, and can make finding a target at close range difficult.
- Ignoring Eye Relief: This number (e.g., 3.5-4 in.) is often on the spec sheet, not the tube. It’s the distance your eye must be from the ocular lens for a full sight picture. Too short can mean getting scoped by the rifle.
- Forgetting Parallax: Scopes set for 100 yards may have parallax error at 50 or 300 yards. An AO or SF feature helps eliminate this, which is crucial for accuracy.
FAQ Section
What do the numbers on a rifle scope represent?
The main numbers (e.g., 3-9×40) represent the magnification range and the objective lens diameter. Additional letters and numbers indicate features like parallax adjustment, reticle type, and turret adjustment units.
What does 4-12×50 mean on a scope?
It means the scope zooms from 4 power to 12 power, and it has a 50mm objective lens. This is a popular configuration for hunters who may need a wider view at lower power and more detail at longer shots.
Is a 3-9×40 scope good for 100 yards?
Yes, a 3-9×40 scope is excellent for 100-yard shooting. At 100 yards, 9x magnification provides a very clear and detailed view of the target, making precise shot placement easier. The 40mm lens provides adequate light for most daytime conditions.
What does the second number on a scope mean?
The second number, after the “x,” is the objective lens diameter in millimeters. It affects how much light enters the scope, which influences image brightness, especially in low light. A bigger number means a bigger lens.
How does magnification affect my shooting?
Higher magnification lets you see distant targets more clearly, but it reduces your field of view and amplifies any movement or shake. Lower magnification gives you a wider view of the area, which is better for tracking moving targets or shooting at closer ranges.
Final Thoughts
Deciphering scope numbers is a fundamental skill for any shooter. Once you know what does the numbers mean on a rifle scope, you can move past confusion and make informed choices. Remember to balance magnification with field of view, consider the importance of lens size for your lighting conditions, and pay attention to the adjustment units. With this knowledge, you can select a scope that truly fits your rifle and your shooting style, leading to more confidence and better accuracy on the range or in the field. Take your time to compare models, and always consider how you’ll actually use the scope in real situations.