Just in the practice session before the final shooting competition, you realize there’s something wrong. You start checking the maintenance checklist for your gun. You tick the proper cleaning, oiling, and alignment of the firearm. What is left then? Yes, you did not correctly evaluate your scope ring height. Why do you need to do it?
Scope ring height is the distance measured from the midpoint of the scope to the thickest point of the tube exterior.
How to determine scope ring height | Basic principle:
The general rule that applies to most firearms is that you should fix the scope ring at the lowest possible level, but the precaution is, it should not touch the base.
It is very critical to place it at an appropriate height. As if it’s too high, it may misalign your shots. On the contrary, it can rub along the rifle barrel if it’s too low before it lies on the front scope ring. An improper elevation of the scope ring can force you to hold your weapon in an awkward position. Consequently, you suffer from recoil and a few other damages.
Factors influencing the height
Many factors help in estimating the appropriate scope ring height. They include the location of open sights, mounts, and other accessories. Your firearm’s action of bolt clearance also interferes with its fixation.
Steps for scope ring height measurement:
There are several simple steps before you finally get an exact size.
» Step one: Gather the supplies you will need:
You should have a measuring caliper or a ruler. The markings should be in millimeters. Take a piece of paper and a pencil.
There are several ways by which you can do this.
» Step two: Take the scope height
⇒ Method one
Mark the center of the ring. From the center of the circle, mark the height where the base rests on the receiver. Record this measurement on a piece of paper. Now you should measure the diameter of the firearm bore.
This diameter is divided by two, and results are again recorded. Now the last recording is of the measurement of the distance between the receiver and scope.
So, they provide you with values for the scope ring height. Since it’s not a very accurate method, so you have to double-check before the conclusive reading.
⇒ Method two:
The objective lens is the lens nearer to the target or aiming object. You will record its diameter in millimeters, add 2-4 mm roughly to it. This is approximately equal to the scope tube exterior. Now divide this aggregate by two. Or you can assess the sum of scope and tube at the objective lens as a whole and take out its half.
⇒ Method three:
You can take two balls of play dough. Put them at the site of scope rings. Now put the scope over them. Press them down to your comfort zone. Now remove the scope and measure the base height at the receiver with a Vernier caliper.
» Step three: Select the right scope rings:
The above scope height gives you a pinnacle from where the center of the scope must lie when resting on the rail.
It would help if you started with the most petite ring. It should also take into account the base measurement above the estimated scope height.
Different companies making these rings have other techniques for their length estimation. You will have to check with your manufacturer for the method they are using.
Some of these calculate the length from the center of the ring to the base of the ring. The value should be higher than the scope height.
Others can approach this by gauging from the inner ring rim to the lower base of the ring. Using this method, you have to add the following values to them according to the scope height.
- For an inch scope tube, you have to add0.5 inches
- For a 30 mm scope, add approximately 0.6 inches
- For a 34 mm range, add 0.67 inches
- For a 35 mm scope, you will add 0.69 inches
You can carry on based on these calculations according to your scope height.
Now once you are done with the scope ring height calculation, you have to double-check your result. After this, you have to fix it. A simple rule is to place the rings as far apart as possible according to your scope.
Once you have put the rings in their respective position, displace the scope, push the ring forward and screw up each circle with a half-inch nut. Use torque wrench of 65 inch-pound for tightening.
However, if you don’t have this wrench, you can work with the half-inch wrench. After one finger tightening, turn the but 90 degrees. But you have to be careful. As if you exceed this limit, you may over tighten it. Another precaution to keep in mind is that never use a foot-pound wrench to overdo things.
Now once you have tightened, the screws and rings are well placed. You can proceed to set the scope in the rings. Furthermore, you will install the remaining screws loosely. Take the short end of the wrench T-15 and start tightening up all of them. You have to make sure that both sides of the rings are equally spaced apart.
To calculate the scope ring height, you first estimate the scope height. Based on this, you choose your scope ring. It is very crucial to have a proper scope ring height. A higher than average level can result in arbitrary aiming at the target.
Whereas a lower level can rub along the receiver base. Both result in recoil and other impact injuries. So you have to keep it to the lowest possible level but, of course, avoiding the frictional rub with the barrel. You have to keep in mind that it is affected by the firearm mounts etc.