Different Guns for different Jobs
Even though all Airsoft guns fire a BB at a target, the means they employ to perform this function can vary. There are several different configurations of Airsoft gun, and each has it's good points and bad making certain types of gun preferable for certain game roles.
Spring guns use a basic cocking mechanism which compresses a spring powered piston. These guns tend to be relatively affordable but slow to fire as typically only 1 BB is loaded per cocking. The exception to this are several models of pump action shotgun which may load 2-3 BB's each time.
Spring pistols are not considered suitable for Airsoft gaming as they leave players at a disadvantage on the field.
Spring rifles are a popular choice for snipers as they are quiet and do not rely on batteries or gas to be carried.
Automatic Electric Guns (AEG) use a hobby motor and gearbox to crank back a sping loaded piston. The mechanism allows fully automatic and/or semi automatic fire modes depending on the model of gun.
The motor is powered by a rechargeable battery (NiMH / LiPoly) which is housed within the gun body or fitted to the outside of the gun in a piece of external mock-military attachment, such as a laser designator.
AEG's are fairly reliable but can be complex and beyond some players' ability to service. This is why it is a good idea to meet other Airsoft club members in your area to ensure you have people willing to help you service your gun and offer advice.
AEG's are the most commonly used type of Airsoft gun and are used in every style of game play from CQB to open field.
Gas guns use a much simpler system than AEG's and the extra kick, sound and realisitc magazine capacities make them popular with military purists. Gas guns use a variety of propellants from specifically formulated Airsoft gas to CO2 and even Propane (camp stove gas). Due to the flammable nature of some of these gases precautions must be taken around their use.
Gas pistols are popular sidearms for most veteran players, offering a compact and reliable secondary weapon where a primary is too big or too powerful.
Gas rifles are less common. This is in part due to the variations that occur with gun power relative to the changes in ambient air temperature. As gas expands or contracts depending on the temperature of the day it can affect your gaming experience.
Gas rifles are popular with snipers as they are easier to cock than spring rifles.