What are the numbers on a Scope?

scopes and the numbers

What are the numbers on a Scope?

A question we are asked a lot of the time is – what are the numbers on a scope for? Also, many of you want to know what is the best scope for airsoft or air rifle shooting and is there a difference. Here, I hope to help you with a few of your questions. Please see our scope and optics page on this website for more information…

The numbers: in a 3-9X40 scope, the 3 means three power or 3X.  This means that the image you see through the scope appears three times (3X) closer than it does with your naked eye. The 9 means nine power, or nine times (9X) closer than it appears with your naked eye. The forty (40) is the objective lens diameter in millimetres. This is a variable scope because you can vary the magnification of the scope from three to nine, stopping anywhere in between. You would describe this scope as a ‘three to nine by forty’. Some scopes have a 3x magnification range such as a 3-9. Some have 4 or more as in a 4-12. Some new scopes have a magnification range of 8x or more.

Most scopes have a main tube that is one inch in diameter. That means that they use one-inch rings. There are several main types of bases that are used to connect the rings to your gun. You need to know what kind of base you have to find out the exact type of the one inch or thirty millimetre rings you will use for your specific scope. The height of the rings is determined mainly by the objective lens diameter, but also the barrel thickness.

The difference between scopes for airsoft guns and air guns – there is no difference, apart from some air guns do not have a Picatinny or Wever tactical rail to fix your scope to the gun, but have a smaller dovetail rail system that needs 11mm fixings for your scope. Almost all airsoft sniper rifles and tactical guns will have the standard tactical rail system to mount your scope. Also, as airsoft BBs do not travel as far as an air rifle pellet, you do not need a very powerful scope to hit the target every shot. This is good news for airsofters as the larger the magnification (power) the more you will pay.

Take a look at our full range of scopes and mounts here at Just BB Guns – the No1 airsoft retailer in the UK.

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