Types of replicas
There are 4 main types of airsoft replica available, known as spring, electric, gas and high pressure air.
The vast majority of airsoft replicas are loaded with ammunition via magazines, in the same manner as real guns. Most modern airsoft replicas have the power system mounted internally so there are no wires or pipes connecting you to the replica and hindering your movement.
Electric powered replicas
The most common replica found at skirmishes is the AEG, automatic electric gun. These are powered by a rechargeable RC car/plane type battery. They operate in the same manner as a spring powered replica, except that the piston is pulled back by a set of gears driven by an electric motor. As such the only input required from the player to unleash fully automatic fire is a pull of the trigger. They all have safety catches and most are capable of firing in fully automatic and semi automatic modes. Some can fire bursts of 3 or more rounds. They are simple to use and cheap to run, requiring you to simply recharge the battery at the end of the game day. Most are very reliable and low maintenance. These factors make AEGs by far the most popular type of airsoft skirmish replica.
Nearly every well known assault rifle or sub machine gun in the world has an AEG counterpart available. Typical AEG’s have a range of about 40 feet and fire 15-20 BB’s per second.
Electric pistols also exist and function in the same fashion, but they are relatively low powered.
Gas powered replicas
Gas weapons store compressed propellant gasses and use a series of valves to release the gas into the hop unit. The BB is then propelled up the barrel as the gas expands. The gas is often contained in the magazine so that a fresh charge is placed into the replica at the same time as the BB reload. Gas weapons do not function well outside of British summertime as the gas will be at lower temperature (and thereby pressure) than was expected by the airsoft designers in East Asia. Gas weapons can also suffer from leakage in the magazine seals and require regular cleaning to function properly. Gas enthusiasts assert that the increased realism of the gas weapons function and its instant trigger response make up for these shortfalls.
The most common type of gas weapon is the gas blowback (GBB) pistol. These appear to function like a real pistol, the top slide moves sharply back when the trigger is pulled and you feel a certain amount of recoil. You will also see GBB rifles, which are less practical, more expensive and generally less reliable than AEG’s but offer an enjoyable firing experience.
You also find 40mm ‘grenade launchers’, often mounted under an AEG, which fire 24-1000 BB’s (dependant on size) in one shot from each grenade shell. These are only really effective in close quarters but the weight of fire will certainly intimidate your opponent!
Gas sniper rifles, non blowback (NBB) gas pistols and gas shotguns are also available but are less common.
The different propellent gasses available are commonly divided into 134a (lower power), green gas (higher power, increased strain on replica) and red/black gas (even higher power). Gas can be bought from shops or at the playing site. Different replicas are designed to use different power gasses. Some players use propane (normal camping stove gas) by using a special airsoft adapter on the can.
Spring powered replicas
The most basic are spring powered replicas. They use a hand operated mechanism to pull a piston against spring pressure and lock it back, whilst loading a BB into the hop unit. The trigger releases the lock and allows the spring to push the piston through a cylinder, rapidly expelling the air inside the cylinder through the hop unit and accelerating the BB down the barrel.
This category includes cheap single shot pistols like the two tones you will see in hobby shops, but also include skirmishable weapons, such as shotguns and sniper rifles.
Spring shotguns are a viable alternative to an AEG, they can be effective and fun to use but require a higher skill level than automatic replicas.
Sniper rifles are the most common spring weapons found at skirmishes. These may fire BB’s to the same or greater range than a regular airsoft replica, depending on many factors, but the main reason to use them is that they can fire with greater accuracy than other airsoft replicas. It is advisable to forget about sniper rifles until you are able to use an AEG well. Most new players harbour a fantasy of being an elite sniper, but new players will fail miserably if they try and learn how to use a bolt action weapon before they have the skill to use an assault rifle in airsoft.