When you look at two rifle scopes side by side, you may notice the product listings can seem like a wall of numbers: 3-9×40, 4-16×44, 30mm, FFP, 0.1 MRAD. Those details aren’t there just for comparison charts. Each one tells you something about the scope you’re considering.
Some describe what you’ll see through the optic. Others affect adjustment, mounting, or how the reticle behaves. Once you know which is which, a scope listing becomes much easier to make sense of.
For RKB Armory customers shopping for used optics, that’s especially useful. Inventory can include different models, generations, and configurations from several manufacturers, so the specifications give you a practical way to compare one available scope with another.
What the Specs Can Tell You
Take a specification such as 4-16×44. The first two numbers describe the magnification range, while 44 refers to the objective lens diameter in millimeters. That’s only one part of the listing, but it’s a good place to begin.
From there, you’ll commonly run into terms such as tube diameter, focal plane, MOA or MRAD, eye relief, parallax, and reticle design. Product listings don’t always explain what those details mean, which can make two scopes difficult to compare at first.
That’s something we see at RKB Armory when customers are comparing used optics from different brands and product lines. Knowing what the terminology refers to makes it easier to understand what you’re looking at and which details deserve your attention.
If you already understand these features and want to know how magnification and reticle design relate to shooting distance, our companion post on choosing scope features for different distances takes a closer look at that side of the decision.
Why Specs Vary Between Optic Types
Not every optic listing gives you the same information. Magnified rifle scopes usually have more specifications to sort through, including magnification range, objective lens size, tube diameter, focal plane, eye relief, and parallax.
Red dots and holographic sights bring different details into the picture, such as reticle or dot size, battery life, mounting footprint, and dimensions. Prism optics have their own combination of specifications, often including fixed magnification, eye relief, and reticle design.
Knowing the type of optic you’re looking at gives those specifications some context. If you want a closer look at the differences between rifle scopes, red dots, holographic sights, and prism optics, RKB Armory’s guide to modern firearm optics covers each category in more detail.
How to Read the Terms on a Scope Listing
Once you know what kind of optic you’re looking at, the next step is making sense of the specifications attached to it.
Magnification tells you how much larger the target appears through the optic. A 3-9x scope, for example, can move from three times to nine times magnification.
Reticle refers to the aiming pattern you see through the optic. That might be a simple crosshair, an illuminated dot, or a more detailed pattern with marks for elevation and wind.
With parallax, the reticle can appear to move against the target as the position of your eye changes behind the scope. Some magnified optics give you a way to adjust for this at different distances.
Eye relief comes into play when you’re positioning yourself behind the scope. It refers to how far your eye can be from the rear of the scope while still seeing the full sight picture, which is particularly important with harder-recoiling rifles.
Focal plane affects what happens to the reticle as you change magnification. Choose FFP, and the reticle appears to grow or shrink along with the image. With SFP, its apparent size stays the same. Tube diameter affects which rings or mounts will fit the scope. Common rifle-scope sizes include 34 mm and 30 mm, though other sizes are available.
Use the Specs to Check Fit for Your Rifle
Once you understand the listing, the next question is whether those specifications make sense for the rifle and the way it will be used. A precision rifle may call for more magnification and adjustment range, while a carbine used at shorter distances may put more emphasis on a simpler sight picture and faster handling.
Precision and hunting optics can vary just as much. Open-country use may favor more magnification, while shorter shots in heavier cover can make a lower-power optic easier to work with.
Before buying, use the specs to answer a few practical questions:
- Does the magnification range fit the distances I actually expect to shoot?
- Is the eye relief appropriate for the rifle and recoil level?
- Will the tube diameter work with the rings or the mount I already have?
- Does the reticle and adjustment system make sense for how I plan to use the optic?
Those questions help turn a long list of specifications into something more useful: a quick check of whether the optic actually belongs on your setup.
What the Listing Can’t Tell You
Knowing how to read an optic listing gives you a much better idea of what you’re considering, but the numbers won’t tell you everything about a used optic. Glass condition, turret function, and the condition of electronic components can matter just as much when you’re comparing what’s available.
That’s where a closer look at the optic itself matters. At RKB Armory, used optics are inspected before they’re listed for sale, and buyers can ask questions about the condition of a specific unit before making a decision.
Once you understand what you’re looking at and know the condition of the optic, you’re in a much better position to compare your options. If you also have an optic that no longer fits your setup, our Sell Your Optic page explains how RKB Armory evaluates used gear.
Frequently Asked Questions
What does 0.1 MRAD mean on a rifle scope listing?
A 0.1 MRAD specification usually refers to how much the scope’s point of aim changes with each adjustment click. MOA and MRAD are two different angular measurement systems used for scope adjustments, so it’s helpful to know which system a scope uses when comparing models.
Does a larger objective lens mean a better rifle scope?
Not necessarily. Going up in objective lens size changes how much light the scope can gather, but size alone doesn’t determine optical performance. A larger objective can also influence the scope’s size, weight, and mounting height.
How can I tell which rings or mount a rifle scope needs?
Start with the scope’s tube diameter, which may be listed as 1 inch, 30mm, 34mm, or another size. The rings need to match that diameter, but you’ll also need to consider the rifle’s mounting system and enough clearance for the scope’s objective lens.
What should I compare when looking at two used rifle scopes?
Once you’ve confirmed that both scopes fit your basic needs, look at their features alongside the condition of each individual optic. Check details such as model number, the adjustment system, reticle configuration, dimensions, and manufacturer information, then review the seller’s description of the glass, controls, exterior, and included accessories.
See What’s Available at RKB Armory
Now that the numbers and terminology make more sense, put that knowledge to use. Browse the current selection of inspected used optics at RKB Armory and compare available options with a better understanding of what each listing is telling you.
