Airsoft guns can be divided into 3 chief categories:
(a) Spring Powered Airsoft Guns (b) Gas powered Airsoft guns (c) Electric powered Airsoft guns
Spring Powered Airsoft Guns: In spring powered guns, the cocking action is through the spring inside the guns. Most of them are semi-automatic and are magazine fed. Spring powered airsoft guns are very cost effective but they have one great disadvantage and that is they have to be hand cocked every time they are fired. This type of gun is perfect for those who have just started playing airsoft due to its sturdiness, availability, and cheap rates. They are not very successful in close combat functions but can be highly effective for snipers, marksman etc.

Gas Powered Airsoft Guns: Gas powered is another type of airsoft gun. The gas blow back guns are the most popular amongst all other gas powered guns. Also known as GBBs, these guns are semi-automatic and fire by employing a gas storage system and some kind of on board system. When the gas is used t bow the pallets out, it is again harnessed in cocking the gun slide back.

Electric powered Airsoft guns: Last but not the least, electric powered airsoft guns also known as automatic electric guns. With the development in technology and a wider response for airsoft guns from different nations, AEG came into being. It composes up of gears to compress and release the piston inside the gun. Due to electrical energy it can generate the power required to make it fully automatic and its ROF (Rate of fire) can go from 600 to 900 rounds per minute.

Image Source: http://www.myairsoftarmy.com/aeg-airsoft-guns/

Airsoft guns are meant to be as realistic as possible with cocking and precision punching, and are aesthetically similar in operation. Unfortunately AEGs fall short on the latter. They very closely resemble real firearms on the outside, the internal operation is entirely different and works more like a radio controlled car than a gun.

Don’t despair though if you have your heart set on getting an AEG, because they do have some definite benefits.

• Reliability

AEGs are impressively reliable, they are able to fire off hundreds of BBs without jamming, overheating or needing to be cleaned.

• Accuracy

The accuracy of airsoft guns or anything that uses a BB as a projectile, will never be perfect. AEGs are much more consistent than most other airsoft guns.

• High capacity for ammunition

All most all AEGs are available with High Capacity Magazines. These magazines hold up to several hundred shots instead of the more common 50 shot magazine. This of course means the user can fire far more shots before reloading, which is very useful when skirmishing.

• Strength

Built around a central metal Mechbox that house the gears and other mechanisms that allow the rifle to function, AEGs are mechanically rugged and reliable, even when exposed to the rough and tumble of outdoor skirmishes. The external strength varies from gun to gun, some are very fragile others are built like tanks.

• Cost effective

The per shot cost of an AEG is very low. They only require electricity to operate, this power is provided by a rechargeable battery pack. Each of these packs can be recharged thousand of times for very little cost and enable you to fire thousands of times per battery. You do not need to purchase gas or disposable batteries for AEGs. The only downside is that AEGs are the most expensive airsoft guns you can purchase, however you get the cost back over the lifetime of the gun.

• Upgradeable

A nice feature of most AEGs is that they are upgradable. You are able to upgrade the power and accuracy, buy add-on accessories and custom modifications. AEGs are also very versatile and cheap to mod, upgrade and repair if and when it becomes necessary to do so.

Source: Arnies airsoft

Picture Source: Hiddenpower

Here’s what you need:

A High Quality Gun. It doesn’t need to be top of the line, but really you want it to be over 350 fps, otherwise it’s not really a “sniper” airsoft and as such isn’t fit for the purpose.

The Right Ammo. Most commonly .20 ammunition is used. For more powerful rifles you will need to use heavier pellets like, .25, .28, and .30.

Adjustable Hop-up. Since it’s possible you are reading this and don’t know what a Hop-up is, let’s cover it fairly quickly. The hop-up system is part of the airsoft gun barrel.  It provides backspin to the pellets allowing for great accuracy and distances. On better quality airsoft guns the hop-up can be adjusted, this is useful because it allows for the use of heavier ammunition, which requires greater backspin to counteract gravity. When a hop-up is correctly adjusted it will allow for more accurate and precise shooting, which is a good thing in general but of the utmost importance if you want to take on the role of sniper. Cheaper airsoft guns’ hop-ups cannot be adjusted which results in less accurate shots, less overall range, and limits the choice of pellets you can use.

The Importance of the Barrel. The longer the barrel the more consistent your shots will be while also allowing higher fps. The inner bore diameter of the barrel also affects the consistency and fps of shots. Also, it’s advisable to purchase a gun that fires at a consistent rate. Having your shots jump from 350-450 every time you pull the trigger is not conducive to good sniping. Use .25-.30 with 400fps and over with an adjusted hop-up.

• Make sure to only buy a rifle with a metal barrel.
• A good quality scope is a must, just make sure the gun is setup properly, otherwise the best scope in the world will not do much good.
• Just because a gun looks amazing, doesn’t necessarily mean it fires well.  Do your research so you don’t end up with a beautiful dud (this can be applied to all things in life).
• You would have to be very very lucky to get a good sniper rifle for $50 or less, as a high-end AEG can probably outrange it, which makes it utterly useless as a sniper rifle. Make sure the rifle you purchase will enable you to act as a sniper.
• Make sure to wear eye-protection that was specifically designed for airsoft, something with polycarbonate lenses.
• You should also consider getting a vest to act as body armor, as there is little fun to be had from getting shot by a pellet traveling at 450fps. You can find airsoft products at Marushin!