If you’re new to riflescopes, the numbers and markings can look like a secret code. Understanding what the numbers mean on rifle scopes is the first step to choosing the right one and using it effectively.
These numbers tell you the scope’s magnification power, the size of the objective lens, and other key features. Getting a handle on this will make you a more informed buyer and a better shooter. Let’s break it down into simple terms.
What Do The Numbers Mean On Rifle Scopes
The most common numbers you’ll see are something like “3-9×40” or “4-16×50.” This is the scope’s model designation, and it holds the core information. We’ll use the example “3-9×40” to explain each part.
The First Number(s): Magnification Power
The number before the “x” refers to magnification. In “3-9×40,” the “3-9” means the scope has variable magnification. You can adjust it from 3 power (3x) up to 9 power (9x).
- 3x (Low Power): At this setting, the target appears three times closer than it does with your naked eye. This gives you a wide field of view, perfect for scanning an area or shooting at close, fast-moving targets.
- 9x (High Power): The target appears nine times closer. This narrows your field of view but provides much more detail for precise aiming at distant targets.
A scope with a single number, like “4×32,” has fixed magnification. It doesn’t zoom; it’s stuck at one power, which can be simpler and often more durable.
The Number After the “x”: Objective Lens Diameter
The number right after the “x” is the diameter of the objective lens in millimeters. In our “3-9×40” example, it’s 40mm. This is the lens at the front of the scope, farthest from your eye.
- A larger objective lens (like 44mm, 50mm) gathers more light. This can mean a brighter, clearer image in low-light conditions like dawn or dusk.
- A smaller objective lens (like 28mm, 32mm) keeps the scope lighter and more compact. It may sit lower on your rifle, allowing for a better cheek weld.
There’s a trade-off: bigger isn’t always better if you value a lightweight setup.
Other Important Markings on Your Scope
Scopes have other numbers that are just as crucial. You’ll usually find these on the adjustment turrets (the dials on the top and side).
Adjustment Turret Numbers
The turrets are used to zero your rifle (align the point of aim with the point of impact). They are typically marked with directions like “UP” and “R” (for Right). The important numbers indicate the adjustment value per click.
- You might see “1/4 MOA” or “.1 MRAD” on the turret.
- 1/4 MOA: One click of the dial will move the point of impact by 1/4 Minute of Angle. Roughly, this is about a quarter-inch at 100 yards.
- .1 MRAD: One click moves the impact by 0.1 milliradians, which is about 0.36 inches at 100 yards. MRAD is a metric system often prefered by long-range shooters.
Knowing this value is essential for making precise corrections after you’ve shot a group.
Reticle Focal Plane (First or Second?)
Some scopes, especially those for long-range, will state “FFP” (First Focal Plane) or “SFP” (Second Focal Plane). This is a more advanced topic, but it’s about the reticle.
- SFP (More Common): The reticle stays the same size as you zoom. The markings (like holdover points) are only accurate at one magnification, usually the highest.
- FFP: The reticle grows and shrinks with magnification. The markings are accurate at any zoom level, which is a huge advantage for holdovers at unknown distances.
Putting It All Together: Choosing a Scope
Now you can decode the specs. But what do they mean for your shooting? Here’s a quick guide:
- Close-Range Hunting (Woods): Look for a low-power variable like a 1-4×24 or a 2-7×33. You need a wide field of view for quick shots.
- General Purpose / Deer Hunting: The classic 3-9×40 is popular for a reason. It’s versatile for shots from 50 to 300 yards.
- Long-Range Target or Varmint Shooting: Consider a 4-16×44, 6-24×50, or similar. You’ll need higher magnification and likely an FFP reticle with MRAD adjustments.
- Low-Light Hunting: Prioritize a larger objective lens (44mm, 50mm) and quality lens coatings to gather maximum light.
Remember, the highest magnification isn’t always best. Atmospheric heat mirage and shaky hands can make very high power (over 20x) difficult to use effectively.
How to Set Up Your New Scope
Once you’ve chosen a scope, you need to mount it and get it zeroed. Here are the basic steps:
- Mount it Securely: Use quality rings and a base. Tighten screws to the manufacturer’s specification with a torque wrench if possible. A loose mount causes all sorts of accuracy problems.
- Get a Rough Bore Sight: You can use a laser bore sighter or simply secure the rifle and look down the bore (with the chamber empty!) to align it with a target at 25 yards. Then adjust the turrets until the crosshair is on the same point.
- Fire a Three-Shot Group: At the range, fire a careful group of three shots at your desired zero distance (e.g., 100 yards).
- Adjust the Turrets: Measure how far the group center is from your aim point. Use the “click” value on your turrets to move the crosshair. If you’re 4 inches low and each click is 1/4 MOA, you need 16 clicks “UP.”
- Repeat: Fire another group and fine-tune. Once your group is centered on the aim point, your rifle is zeroed. Some shooters forget to record their final settings for future reference.
Frequently Asked Questions (FAQ)
What does 4-12×50 mean on a scope?
It means a variable power scope that zooms from 4x to 12x magnification, and it has a 50mm diameter objective lens. The larger 50mm lens is good for low-light situations.
Is a 3-9×40 scope good for 100 yards?
Yes, a 3-9×40 is an excellent choice for shooting at 100 yards. The 9x power gives you plenty of detail for precise shot placement, and the 3x setting is great for getting on target quickly.
What is better, a 3-9×40 or 4-12×50 scope?
It depends on your use. The 3-9×40 is more versatile for general hunting. The 4-12×50 offers more magnification for longer shots and a bigger lens for low light, but it will be heavier and might sit higher on the rifle.
What does “MOA” stand for on a rifle scope?
MOA stands for “Minute of Angle.” It’s a unit of angular measurement used for scope adjustments. For practical purposes, 1 MOA is about 1 inch at 100 yards, 2 inches at 200 yards, etc. So, a 1/4 MOA click moves the impact ~1/4 inch at 100 yards.
Final Thoughts
Deciphering what the numbers mean on rifle scopes isn’t as hard as it first seems. The main formula—magnification x objective lens size—gives you the basics. Paying attention to the adjustment values (MOA or MRAD) and understanding focal planes will take you to the next level.
The best scope for you is the one that matches your rifle’s purpose and your shooting style. Don’t get overly focused on just the highest magnification number. Consider weight, light gathering, and field of view. With this knowledge, you can confidently read those spec sheets and choose the perfect optic for your needs. Now you’re ready to hit the range and put that new understanding to the test.