Rifle Scope Glossary

[SheriffHD]

This information is taken from hand books which i was given by From the NRA when i first joined, as many of the guys on this site enjoy sniping, or even those who wish to get to know a little about scopes, this will just be a quick basic read.

Enjoy

Rifle Scopes Glossary Of Terms

​

Descriptions of rifle scopes can be a little confusing at times, especially if you're new to scopes and shooting.

Here are the basics;

What does 4x20 mean?

• 4 - The first number means the magnification. In this example it is 4x (4 times) normal eyesight.
  
• 20 - means the diameter of the viewing lens (not the eyepiece) in millimeters. (the tech term for this is "Objective lens size"
  
• 4x20 - Therefore the scope is 4x magnification seen though a 20mm wide view lens.
  

And what about 3-9x40 then?

• This means the scope has variable "zoom" capability.
  
• In this case it ranges between 3 and 9x magnification though a 40mm wide view lens (objective lens)
  
• Unless otherwise stated the numbers are Whole numbers, so on a 3-9x there will be a 3, 4, 5, 6, 7, 8 and 9x position
  but not fractions or some sort of granular 3.75x type of thing.
  
• 3-9xx40 is the most popular general purpose scope size. If you can afford one get one.
  

Time for the more Tech stuff now

​

Exit pupil: The size of the column of light that leaves the eyepiece of a scope.

• The larger the exit pupil, the brighter the image.
  
• To determine the size, divide the objective lens diameter by the power ( a 4x40 model has an exit pupil of 10mm)
  

This is why big mag scopes tend to have big lenses e.g. 8x56 and why you dont get 3-9x20,

Because basically they would be rubbish.

Eye Relief

• The distance a scope can be held away from the eye and still present the full field of view.
  
• Unlike cartoons you don't have the eyepiece pressed up against your eye, if you did you are sure to get a black eye from recoil.
  

Field of View (F.O.V) : the side-to-side measurement of the circular viewing field or subject area.

• It is defined by the width in feet or meters of the area visible at 100 yards or meters.
  
• A wide field of view makes it easier to spot game and track moving targets.
  
• Generally, the higher the magnification, the narrower the field of view.
  
• Which is why variable magnification scopes are so handy. Spot the target at low mag and. Lock on and zoom in.
  

Windage & Elevation - The 2 turrets mid way down the scope body that are a key part of zeroing a scope.

When you fit a rifle scope they are up and to the right.

Windage - The one of the right

• As the name suggest it is to do with wind
  
• It adjusts the crosshair minutely left and right.
  
• And for in the field adjustments for wind strength where, for example a high crosswind will make long range shoots veer slightly.
  

Elevation - The top one. Up and Down basically.

• Again critical for getting zero and in the field where a strong head of tail wind effects a pellets lateral trajectory.
  

An experienced shooter will use the these turrets to make a situational zero adjustments. If you're not experienced don't worry. Just be aware and experiment as that's how you become experienced

Parallax:

• A condition That occurs when the image of the target is not focused precisely on the reticule plane
  
• Parallax is visible as an apparent movement between the reticule and the target when the shooter moves his head or, in extreme cases, as an out of focus image.
  
• Some scores, higher priced ones typically, have parallax correction built in so that this focus problem does not occur.
  

That is it for this guide, will post more.

as i have just found pretty much all the documents that i was given from the NRA, even got a few army guides (Canadian army though) Which i will post on here at some point

Enjoy

 

[Sniper_88]

Are you going to cover the recticles and thier use?