I have 3 airsoft guns, and they are convincing replicas (Steyr Aug with the Phantom silencer mod, M16A2 and MP5K. You should see the new full-metal M4 from Classic Army. It's difficult to tell it apart from the real one until you actually have one in your hands.
Airsoft is not supposed to be a sport for countries where gun laws are strict, and it is VERY popular in the US.
It's perfect for having a great time with your friends while playing combat games.
I tried paintball but I prefer Airsoft, even with the "inmortals".
Daniel