The Japanese and other Asians have known about Airsoft BB guns since the 1970s when they first developed. In Japan especially it was extremely difficult to buy real weapons so exact copies of modern day military and civilian weapons were produced, the ammunition that they used was a small diameter plastic BB or pellet as they are most often called.
As the Airsoft weapons started to drift to the US, people began to see that it could be a great sport. Airsoft is a combination of a lot of things, physical endurance, strategy and awareness of historic battles being a few. Originally the guns that were produced were either spring or gas operated. Spring operated weapons were then and are now, the least expensive and are often the first gun purchased by a new entrant to the sport. Once the person becomes hooked, he or she will then buy Airsoft guns that are gas operated. A gas operated weapon gives the benefit of rapid fire, the gun can fire single shot, semi auto or full auto; a spring operated weapon on the other hand is single shot only as the “soldier” has to manually cock it for a subsequent shot.
Airsoft GI BB guns and BB guns look very much the same; both are very close replicas of actual modern weapons. That is about where the similarity stops. BB guns are never used in this game of simulated combat as they use metal balls as ammunition, they have a longer range and they shoot at a higher velocity. This combination of metal ammo, high velocity and long range can add up to a situation that Airsoft aficionados certainly do not want. Sure, there are all kinds of tactical gear available but it is not designed for this.
BB guns are used for a totally different purpose, target shooting. They are never to be used in any circumstance where there is the possibility of injuring a person or even a pet.
Airsoft is for fun, the combatants can make up the rules as they go along or they can play games that have somewhat fixed rules. Although two players can enjoy the game, it is usually more fun when it is two teams, when this is the case, historic battles can be simulated and tactical warfare can be practiced just as if the players were in the real battle.