What type of optic should I use?
There are 2 basic types of optics to consider, scopes and red dot sights.
Scopes
A scope gives you a magnified view of what you are aiming at as well as see things further away. You would typically want to mount a scope to DMR airsoft rifles or airsoft sniper rifles. A DMR is a designated marksmen rifle. These rifles were designed to increase the effective range of a squad by giving more precision and accuracy needed over the standard issued rifles in the platoon. In the context of airsoft, it is a rifle (AEG) that is modified to shoot harder than other regular rifles. Various events and fields have their own subset of rules just for this type of rifle but generally speaking, there is a trade off when you go with a DMR. You are usually restricted to semi-auto with a minimum engagement distance rule in effect to maintain safety and help balance the gameplay.
Let's go over some terminology to help you better understand how to select a scope. For a scope you will usually see a number which denotes the important specifications of the scope. For example you might see 10x50. The first number is the amount of magnification the scope has, and the second number is the objective lens diameter, or the size of the lens on the end of the scope (muzzle end). Larger objective lens diameters means the scope gathers more light which gives you a brighter image through the eyepiece. For scopes that have adjustable/variable magnification the numbers will look something like 3-9x40. The 3-9 would denote three to nine magnification and the second number is still the objective diameter which in this case is 40(mm).
When you get a scope you will have to attach scope rings to it to mount the scope to your rifle. For scopes that come packaged with rings, most of the time these rings will be picatinny or weaver style rings. For airsoft be sure you get the picatinny (milspec-1913) rings as no airsoft guns are made with weaver in mind. If your scope does not come with rings then you will have to measure the main tube (body) of the scope in order to get the correct size rings. The majority of scopes out there will be either a 30mm or 1 inch main body diameter. Some rings come with adapters that allow you to use the same set of rings on either 30mm or 1 inch scopes.
The reticles on the scope might be a simple crosshair or one with different markings to assist in range finding. Additional features on a scope may include illumination on the reticle which helps in low light situations.
For DMR type rifles, a low magnification or fixed power scope is sufficient. If you have too much magnification it might actually make you slower because you are seeking a target in a zoomed in picture rather than having a wider field of view like in a lower power magnification. On a sniper rifle you can get away with a low power scope because airsoft ranges aren't extreme, but being able to dial in on a high zoom is also nice. Be sure to protect your lens with a lens protector!
Red Dot
Red dot sights are great for fast target acquisition. A red dot allows you to keep both eyes open to keep your situational awareness when playing and quickly engage targets. It is also a great option to use in low light in low light engagements. Since airsoft guns have limited range, most of the engagements take place within 150 feet, for this reason magnification may not be as beneficial as the ability to quickly acquire your target. For these reasons, the red dot is one of the most popular airsoft accessories.
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Q & A:
Q: Should I use a red dot or a scope?
A: This depends on your mission. Most standard AEGs do best with a red dot sight. If you decide to build a DMR, a magnified scope is an essential piece of equipment.
