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How to Measure Scope Ring Height Properly [Beginner’s Guide]

Scope Ring Height

Got a brand new rifle scope you want to mount, but don’t know how to properly measure your scope ring height?

If your answer is YES, this article is for you!

We’ll cover everything in detail, and we even have some tidbits about scope height. Some of them are even followed by law enforcement agencies!

Tools to Help You Determine Your Scope Height

Here’s a list of useful tools you’ll need to help with measuring ring height and adjusting them as necessary:

  • Calipers: Arguably the best way of getting an accurate measurement for firearm-related work (like the distance between your scope and receiver).
  • Ruler: Results in a rougher-quality estimate. You’ll have to rely on your eyes and holding the ruler level. 
  • Gun Vise: This keeps your rifle secure. It also has spaces that allow you to set your screws and other parts aside.
  • Torque Wrench: This lets you tighten down everything according to the manufacturer’s specifications.
  • Crosshair Level: This, in combination with your gun vise, ensures your horizontal crosshairs are level.
  • Boresight and Targets: These should help you zero in your scope.

How to Measure & Determine Scope Ring Height

Here are the most common ways manufacturers measure and determine scope ring height.

Measuring scope ring height involves a bit of math, but don’t worry — they’re simple enough.

1. Measuring From Base to Ring Center

To give you a look at the equation, it’s:

(Diameter + 2 to 4mm) / 2 = Center Height

We’ll break this approach down into three simple steps:

  1. Measure your objective lens diameter, which should be measured in millimeters. You can also look at the second number in your scope’s designation (The 40 in 3-9x40mm).
  2. Your next step is to add 2 to 4mm. This accounts for the thickness of the scope body. You can also get the exact measurement from the manufacturer.
  3. Divide your result by half. That number should be dead center!

2. Measuring From Base to Ring Edge

As for this method, just do the following:

  1. Get the measurement of your scope tube and divide it by 2. The scope tube is typically 1 inch or 30 mm. 1 inch is equal to 25.4mm, half of which is 12.7mm.
  2. Add the manufacturer’s scope ring height.
  3. To account for your objective lens, just divide its measurement by 2. Don’t forget to make sure that the result is smaller than your scope height to not hit the barrel.

The Importance of Proper Scope Ring Height

We’ll briefly walk you through some key reasons why measuring scope height correctly is so important.

#1 It Affects Your Accuracy

Having your scope too high or too low will either force you to shoot in an awkward position or put pressure on your scope.

This will make landing accurate shots more difficult!

#2 You’ll Avoid Damaging Your Scope and Hindering Your Rifle Bolt

The right height of your scope ring places less pressure on your scope.

This will lessen its tendency to suffer any damage.

When using a bolt-action rifle, having your scope mounted too low can interfere with bolt clearance! 

#3 You Can Avoid Issues With Parallax

Improper scope ring height can lead to issues with parallax.

This creates a black halo or “ghosting” effect around your lens, which results in difficult target acquisition!

#4 It Can Affect Ballistics App Calculations

Knowing the right height for your scope rings will especially help with precision and long-range shooting.

Serious ballistics apps use it for their calculations!

Common Issues With Scope Ring Height

Mounting your rifle optics should be pretty straightforward. In a gun shop, properly measuring scope height can be done through observation, familiarity, trial and error.

However, for the inexperienced or online shopper to do that, they’ll have to:

  1. Buy multiple rings
  2. Test them to figure out which ones work
  3. Return what remains

Simply put, it’s costly and time-consuming. To avoid that, we’ll talk about some issues when you try to determine scope ring height correctly.

1. Using Old Scope Rings

Others make this mistake, either to save money or just for the sake of using old classics. However, buying new scope rings for your rifle scopes is the way to go.

This will also benefit you more over the long-term, since getting brand new accessories means no wear and tear and having all the appropriately-sized screws.

2. Mismatched Bases, Rings, and Mounts

Not having the right type of scope rings and mounts that match can cause issues with getting the right height. Make sure you get brand new bases that properly fit the type of rings you’re after.

Also, try to match their brands for the best fit you can get. If your gun has an integrated rifle scope mount machined into its receiver, it’s going to be one of the following:

  • Dovetail
  • Weaver
  • Picatinny

A dovetail mount can only use dovetail rings. Both Weaver and Picatinny rails, on the other hand, can use Weavers. Don’t forget to check if your mount is a dovetail, Weaver, or Picatinny rail. 

3. The Scope Ring Height Is Too LOW

Normally, having your scope mounted as low as possible is best. However, there are multiple reasons NOT to have a low scope height:

  • Properly Tightening Your Front Scope Rings Will be Difficult: When your scope is mounted too low, your objective lens usually hits your gun barrel. In this instance, you can’t properly screw your front scope rings without crimping the scope tube.
  • It Gets in the Way of Bolt-Action Rifles: When using a bolt-action rifle, you have to watch out for the handle’s clearance. Having it hit your scope means replacing the bolt or working the action.

4. The Scope Ring Height Is Too HIGH

Always try to make sure that your rings aren’t too high. Try to make their height as low as possible without touching any other parts of your rifles.

In this type of setup, your rifle scope will provide you with the most accuracy. Also, having your rifle scopes mounted too high can cause various issues such as:

  • Feeling More Recoil on Your Shoulder: This results from improper posture. This is caused by having to take an awkward position to get a proper sight picture.
  • Taking a Hit on Your Chin: This can happen when using a high-recoil caliber. It’s because you’ll have to separate yourself from the cheek weld and lift your head up to peer through your scope.
  • Scope Damage or Failure: A higher scope can suffer from this because of extra recoil.
  • Lower Accuracy: Some owners spoke of finding it difficult to land accurate shots despite zeroing their scope multiple times.

What Height Scope Rings Should You Use?

These are your typical guidelines for proper scope height. They’re based on objective lenses and a standard tapered barrel:

  • Low: 40-42mm
  • Medium: 44mm
  • High: 50mm
  • Extra-High: 55mm+

As for other considerations, just take note of the following:

  • For iron sights that are higher, either remove them (only if they’re designed for it) or have your scope mount a bit higher.
  • For larger objective lenses meant for long-distance or precision shooting, get higher scope rings.

Choosing the Best Scope Ring for Your Scope

Up next, we’ll walk you through the key considerations you should keep in mind during your search for the best scope ring. Finding the best-fitting scope ring boils down to these factors:

#1 Your Rifle’s Mounting Platform

This normally determines the type of rings you will buy. Just make sure to double-check whether your rifle has a dovetail, Weaver, or Picatinny rail.

However, the main advantage of a Picatinny rail is that it’s compatible with any set of rings and other accessories.

#2 Your Scope’s Size

For this, you’ll need to know the diameter of your scope tube and your scope height. The vital aspect, however, is finding one that can accommodate your objective lens diameter.

It can get problematic too. Most scope rings come in low, medium, or high, but their specific numbers differ from one manufacturer to the next.

It will require a bit of research, probably a little trial and error too.

PRO TIP: Don’t forget to double-check manufacturers’ websites for the exact specs!

#3 What You Find Comfortable

At the end of the day, what you find most comfortable when shooting matters.

Having an exact number or measurement is good, but trying to land accurate shots from an awkward position is a sign of improper scope ring height.

Just make sure the ring’s width is the same as your scope’s diameter. The width of your scope ring has to match the diameter of your scope to secure the optic of your rifle. Adjust if necessary.

Other Basics

Here are some other basics you should know:

    1. You can assume that a larger diameter means a pricier and heavier scope.
    2. A scope tube typically has this range of diameters:
      • 1 inch
      • 30mm
      • 34mm
    3. There are different ways of attaching various scope rings:
      • You can simply screw some in by hand
      • Others would require hex tools

Frequently Asked Questions

Now that you know how to properly measure and choose the right heights for your scope rings, we’ll just answer some possible questions you might still have.

1. What Size Rings Do I Need for a 30mm Scope?

Typically, the proper rings have to match the diameter of your scope tube. As an example, a 1-inch scope would need a 1-inch scope ring.

The same applies for a 30 mm scope. It would need a 30 mm scope ring.

2. What Ring Height Is Best for a 40mm Scope?

We’re basing this tidbit on an AR-15’s absolute co-witness height for the center of the scope glass. Typically, it’s 1.46 inches.

That leaves enough space for a 40 mm objective, which is 1.58 inches. This should work even for a 50-mm objective, and you’ll still have room to spare. To be sure, you’ll need high or extra-high rings.

3. Do You Need High Rings for a 50mm Scope?

Yes, you do. Generally, low to medium ring heights aren’t good fits for a 50-mm scope.

They’re too low. Other users end up spending lots of time and money before finding this out.

4. What Ring Height Is Best for a 56mm Scope?

For 56mm scopes, you’ll want a high scope ring height. Normally, this would apply to an objective with a standard barrel contour.

Conclusion

Trying to determine the right scope ring height is pretty simple, but many considerations go into it.

We’ll leave you with these points:

  • You can measure from the base to either the edge or center point of your objective lens.
  • Having a dovetail, Picatinny, or Weaver Rail largely decides what ring you’ll buy.
  • Don’t screw your rings too tightly. You could strip your threads
  • Don’t forget to adjust and customize your ring height to the point that it’s comfortable.
  • Lastly, search for high-quality scope rings!

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