Riflescope rings are an essential component in any shooting setup. They securely hold the scope in place and provide the shooter with a stable platform to sight and fire their rifle. There’s more to choosing scope rings than just knowing what diameter they are: there’s ring height, positioning on the rifle, and even whether you’re using a cantilever.
In this article, we will cover everything you need to know about riflescope ring sizes and how to select the right ones for your shooting needs.
What Size Scope Rings Do I Really Need?
When it comes to riflescope rings, size does matter. If you try to use the wrong size of scope ring on your scope, the best case scenario is that it takes a while to damage your scope. It’s much more likely to damage your scope immediately. So the answer to this question is: you really need the size of rings that matches your scope’s tube diameter.
Every scope I have ever seen has either been 1-inch, 30mm, or 34mm. If you still have the original packaging of the scope or any documentation about it, you should be able to find out what size tube it has pretty easily. If not, a trusty tape measure can help you do the trick.
In terms of whether you need low, medium, or high scope rings, that will depend on the mounting platform of the rifle and the size of the objective lens (bell) of your scope. If your rifle has a picatinny rail on top to give it a little extra space, you are less likely to want medium or high rings, but if you’ve got a scope with a 50mm objective, it becomes much more likely.
Factors to Consider When Assessing Scope Rings
The Diameter of Your Scope
The first and most obvious factor to consider when selecting scope rings is the diameter of your scope. This measurement will be one of three options: 1-inch, 30mm, or 34mm. Your scope rings need to match the tube diameter. Using an incorrect size will not work and you are likely to damage your scope if you try to do so.
The Eye Relief of Your Scope
Eye relief refers to the distance between the eyepiece of the scope and your eye when you’re looking through the scope. The eye relief of your scope will impact the position of the scope rings you need to achieve a comfortable and accurate shooting position.
For example, if your scope has a short eye relief like a Trijicon ACOG, then you’ll need to position the rings as close to your eye as you can. With a scout scope (riflescope designed for use on scout rifles), you’ll need to move the rings much further away from your eyes.
The Size of the Scope Bell
The size of the objective lens, or the scope bell, is another important factor to consider when selecting scope rings. The larger the objective lens, the higher the scope rings need to be to allow for proper clearance and prevent the scope from touching the barrel or top of the handguard.
The size of the objective diameter is noted in the name of the scope, usually shown as something like 3-9x32mm. For the most part, the bell won’t really affect how high of rings you need unless you have an objective larger than around 32mm. Larger may still not be a problem if you are mounting onto a picatinny rail which itself is mounted on the rifle.
Your Shooting Style
A lot of military-trained folks shoot NTCH, or nose-to-charging-handle. This positions your eye further forward than most civilian or law enforcement-trained shooters. To make sure your eye is in the correct position relative to the ocular lens, you’ll need to scoot the scope rings forward (and consequently the scope itself) to match.
There isn’t one “right” way to shoot, though it’s true that there are plenty of wrong ways to shoot. However you prefer to hold your rifle, keep in mind that it can affect what style of rings you use with your scope. For example, I wasn’t able to use the rings that came with my LPVO because my shooting stance required a cantilever to hold the scope further away from my eye.
Situations like that are very common.
The Purpose of the Rifle
This factor won’t affect the size of the rings or their height, but it will affect what mounting system of rings you buy. There are several different mounting systems available, including fixed, quick-release, and one-piece mounts. Each system has its own pros and cons, so it’s important to consider the purpose of the rifle and your personal preferences when choosing a mounting system.
Quick-release mounts are convenient for shooters who may need to quickly remove and re-attach their scope, while one-piece mounts provide a more solid and consistent zero without the small fluctuations that tend to come with QD (quick detach) mounts.
Cantilever vs. Straight Rings
As I mentioned above, I needed to buy a cantilever mount separately to get my LPVO to fit comfortably for me. A cantilever mount comes up at an angle to let the scope sit further forward or further back than the rail would allow with straight rings. Here’s an example:
Cantilevers are generally only an option with picatinny rails as far as I know, so if you’re mounting directly to the action of the rifle you may need to mount a rail adapter first if you want to use a cantilever.
Straight rings are the standard set of 2 that lift straight up and can be positioned independently from one another. They’re nice precisely because you can adjust the distance between the two rings to accommodate different scopes.
How to Calculate and Measure Scope Ring Sizes
Once you have taken into consideration the factors mentioned above, you can use a tape measure to accurately measure the size of your scope and determine the correct height for your scope rings.
There Are Three Main Sizes of Scope Rings
I touched on this briefly above, but here’s more info on scope ring sizes.
This is the smallest tube diameter, and is generally reserved for LPVOs and budget long-range scopes. The 1-inch form factor is nice because it’s cheaper, but it’s also known for letting the least amount of light through. If you go with a scope that has a 1-inch tube, you can expect to have a somewhat darker image than an equivalent scope with a larger tube.
With LPVOs, this isn’t really a problem because you’ve got so much light anyway (the more magnification = the less light). That is why you’ll see high-end LPVOs with only 1-inch tubes.
This is the most common for scopes with higher magnification. You get more light making its way to the ocular lens, which becomes a lot more important as you crank up the magnification. 30mm tubes are also stronger and more durable than 1-inch tubes when everything else is equal. Since long-range shooting is typically done with larger calibers, the extra durability matters.
This size seems to be coming up more and more these days. The high-end long range scopes will be more likely to have 34mm tubes instead of 30mm. Every advantage that comes with 30mm also comes with 34mm and then some. More light, more durability, etc.
There Are Three Main Heights for Scope Rings
Scope ring height also gives you three main options: low, medium, and high, though I’m not exactly sure how tall each option is. The height of the rings you choose will depend on how large the objective lens diameter of your scope is and how you’re mounting your scope to your rifle.
If you’ve got a massive 56mm bell and you’re trying to mount directly to the top of a bolt action rifle, you will probably need high rings. If you’ve got a tiny 24mm objective and are mounting on a picatinny rail, you probably need low rings. Anything in between and it’s anyone’s game.
What Scope Did the Rings Come With?
If you purchase a scope and ring set, the ring size should match the scope size. In this case, you don’t have to worry about measuring or selecting the correct ring size. Simply follow the manufacturer’s recommendations for installation and enjoy the peace of mind that your scope and rings are perfectly matched.
Worst Case: Just Use a Tape Measure
If you’re still unsure about the size of your scope or the height of the scope rings you need, the simplest solution is to use a tape measure. Measure the diameter of the scope to determine the correct size. Since there are only three options, you can confidently decide on the one that is closest to what you got looking at the tape measure.
What Can I Do if My Scope Ring Is the Wrong Size?
Buy new ones. You cannot use the wrong size of scope rings with your scope. No amount of lapping, taping, or other Macgyvering is going to get you to a point where
- Your scope performs optimally.
- Your scope is not damaged either immediately or over time.
It’s likely that your 50mm scope will need high rings. It may only need medium depending on your rig, but I’d be very surprised if it would work with low. If you’re mounting directly to the action, I’d start with high rings. If you’re mounting to a picatinny rail, it’s harder to choose between medium or high.
The larger the bell, the higher the rings. A lot of times the Q&A and the scope reviews that you’re looking at are very helpful with this. People will ask about mounting the scope on a specific rifle, and knowledgeable people provide specific answers on specific combos.
Generally no. The reason you’re adding height is so the bell can sit without touching the top of the rifle. It’s possible that if you had a scope mounted on high rings when only low was necessary, that you would need to adjust elevation more as you changed distances, particularly for extremely short-range shots (assuming a 100-yard zero).
Selecting the right size scope rings is an important task that can impact the accuracy and stability of your shooting setup. The wrong size rings simply will not work with your scope, and if you try and force it you’ll just end up breaking something.
The height of the rings is something you determine based out of necessity – you only want the scope as high as it needs to be in order for the bell to clear the top of the handguard or barrel. I don’t think I’ve ever seen taller rings used to accommodate the comfortable placement of a shooter’s eye. It’s much more common for shooters to need to raise their cheek weld to meet the scope.
If you have any questions or important tidbits to add to this, feel free to let us know in the comments or hit me up on Twitter @cameroncporter.