Let's talk about optics and what they can do for you. If you are a keep-it-simple type of player, this discussion is probably not going to apply to you. If you are in the market to purchase an optic or trick out your gun, this will prove relevant.
There are numerous types of optics out there so let's talk about the common types and what they are suitable for. Before we begin, we will assume your gun is performing correctly as it should and that your hopup is adjusted correctly.
A red dot sight is a zero magnification optic that casts a simple dot onto a piece of glass. The dot is what you will impose over your target and fire. It is intended to be faster than a traditional set of peep sights in which you must line up the front and rear sight. The red dot does not offer any zoom to your sight picture and works great at any range, but it is most advantageous up close and at medium ranges. Airsoft dot sights might come in other colors and the reticles too. You can hold your face as far or as close to the optic and it will not affect how it functions. Some types of optics cannot be viewed properly if your eyes are not at the proper distance from the scope. This is called eye relief.
A rifle scope is a magnified optic. These have a specific eye relief so mounting it to your gun properly is crucial. Scopes will usually have their magnification levels and objective lens diameter in the model names. For example, a 10x40 means 10 power by 40mm objective lens diameter. A variable powered optic will list its magnification range as the prefix, so a 3-9x40 means 3x to 9x power, by 40mm objective lens. These types of scopes have a specific set eye relief so mounting it correctly and then having your eyes at a proper distance are important to viewing through the glass with any sort of clarity. Most airsoft grade scopes will be second focal plane scopes, which means the reticle does not get larger when zoomed. A first focal plane scope will have the reticle get larger if zoomed in. To keep things simple and without going into it much, the ranging reticle is affected by this but in airsoft this is hard to take advantage of and you won't find it in a cheap scope. Moving on we have the...
Short Dot Scope / Low Powered Variable Optic
A short dot scope is supposed to bridge the gap between the quickness of a dot scope with the flexibility to work at longer ranges like a magnified scope. This is accomplished by having a 1x or near 1x (zero magnification) setting. With the way our eyes work, when you aim with both eyes open, even with that tiny bit of distortion, you can see that reticle or dot the same way you would a red dot scope. The magnification is of benefit at medium to longer ranges, so this type of scope can do more at the expense of weight and sometimes more tricky eye relief.
This type of setup is another way that people have bridged the gap with their optics package to give them more flexibility. What you have here is a red dot sight and a magnifier optic behind it. The magnifier zooms in the picture you see in your red dot optic, giving you the magnification you might need to shoot or ID things moderate ranges. When you want to use your gun for CQB, you can move the magnifier out of the way and you are back to having a fast setup for up-close engagements.
Dot sights are the quickest in close range and low light scenarios. The cons to a dot sight are obviously lack of magnification. Whether you need or want magnification is subjective but it can be supplemented with a magnifier or running a short dot altogether.
Magnified optics have tremendous advantage when it comes to target identification, surveying an area, and working in tandem with your airsoft gun to give you better effective range. The cons to this are having your sight picture zoomed when trying to shoot up close is a tough thing to overcome. Having too much zoom is not good either because you might not see what else is going on around your target.
Everything beyond a simple dot sight also adds a fair bit of weight. That bit of heft might be unpleasant to some people. Some of you might be sitting at home adding or removing stuff to your gun only to realize how much more pleasant and easier to handle the gun becomes.
With that, I don't think I have to explain what types of sights work on what combination of guns. Support your local store by shopping local and getting a look through some up close. We also have numerous types of sights and scopes on our website. If you have more questions feel free to reach out and contact us. Thanks!