Rifle scope mount rings are every shooting retailers biggest "no defect" return product type.
And of the various return reasons ring height (too low or too high) is the number one return reason.
This guide walks you through the correct order of checks so that you get it right first time.
Step 1 – Check Your Scope Tube Diameter (the easy one)
Start with the scope tube size. Clearly the scope tube and ring diameter must be the same. If the tube size is wrong, nothing else matters!
>> 1 inch (25.4 mm)
>> 30 mm
>> 34 mm
Step 2 – Correct Rail Type (Weaver/Picatinny, Dovetail, Proprietary)
Always confirm rail type on the rifle before choosing rings. Not going into this here, it's an article in itself, so assuming you know or can find out easily.
Fast Filter Tip - Say you are after some 2 piece rings. On site you can go to that section and Filter by Ring Diameter and Base type to instantly clear the noise. Click the image below and have a go.
Step 3 – Get the Height right
Rings are normally described as “Low / Medium / High / Extra High”. The problem - and this is what causes the returns - is that there is no standard for what “low”, “medium” or “high” means. One brand’s “low” can be another brand’s “medium”. They often even vary within brands ranges, being relative to each other. So really they are rough guide labels to start from. If you buy only on the basis of “low / medium / high”, the chance of error is much higher.
Key height factors
To start you need to know the scope objective casing "Outer Diameter" (OD) This is not the same as lens diameter.
You don't want it sitting to high as it may cause shooting position problems and not so low that it just won't fit or touches the barrel or guard (very bad = returns)
Example Simple Method
1) Measure the scope objective case outer diameter. For example, a “50 mm scope” refers to the lens diameter, not the outer housing. The outer housing is typically ~57–64 mm depending on whether the scope has an adjustable objective (AO) housing.
Here, a Hawke 4-16x50 scope, outer is 57mm
Rough Guide to help you filter a shortist: Scope Objective (Outer Housing) > Typical Ring Height Needed
>> 28–32mm OD - Very low / Low
>> 40mm OD (≈45–54 mm outer) - Medium / High
>> 50mm OD - High / Extra High
2) Now you have some options check the mounts you are considering. What is the height from base to ring center?
a) Example here - 26mm. Multiply this by 2 = 52mm. We suggest deducting 2mm (=50mm) from this to give a minimum 2mm clear between scope to gun (assuming flat body) so that recoil vibration does not cause contact.
b) Compare the result to the scope outer diameter. In our example the scope outer is 57mm so these mounts are too short.
However - Base Rail Factors that may affect the result
Our example above is based on a flat base.
If your rifle has a raised rail, stepped base, short body meaning scope will hand over a gap above barrel - then this adds height and you may be able to use the "too short" mount after all or even go lower.
If the rifle though has a top load magazine, high front iron sight you want to clear or maybe a bolt action that may foul a scope turret then you may need to go higher.
How to calculate base to ring center if you only have base to ring bottom?
Some listings. Sportsmatch for example, only show the base to ring bottom, not center. if so, how to get the base to ring center?
Easy - Get the base to ring bottom and add half the ring diameter. Example: 11mm base to ring bottom works as:
>> 1 inch ring = 11 + 12.7 = 23.7mm
>> 30mm ring = 11 + 15 = 26mm
>> 34m mount ring = 11 + 17 = 28mm
So a final Quick Checklist Before You Buy Rings
✔ Tube diameter matches your scope
✔ Rail type confirmed (Weaver/Picatinny/Dovetail/Proprietary)
✔ Adapter selected if needed
✔ Objective outer diameter checked
✔ Rail height considered
✔ Ring height chosen in mm, not by “low / medium / high” label
Not sure?– Ask Before You Buy. We've been doing this for years, we'll get it sorted for you.
Tell us as much as you can on:
Scope model
Rifle model
Rail type
Objective size
With those four details, ring height can be chosen correctly almost every time.
