Airsoft guns are not Illegal in our country, as long as they follow some basic safety laws. A gun is "not" considered a replica as long as it shoots over 366 FPS. It wouldn't hurt for you to do some research either. There are some great discussion threads and links on these forums to the information you seek.
As far as the authorities go, you will now have a report about you. But have no fear my friend. As long as you are polite to the authorities, and are a law abiding individual there is nothing to worry about. Owning, operating, cleaning, etc an airsoft gun in a private residence is not in itself a crime. Never ever use it in a threatening manner, and if discharging it indoors is scarring your neighbors; maybe find a more appropriate place to shoot it. This is a good place to start asking questions, and I appreciate that you sought help from our community, and apologize for those who wasted your time with non helpful remarks.
Your concerns are legitimate, but I think you'll be alright my friend.
ďREALITY IS LIKE A STONE. TO MANY ITíS HARD AND COLD, THEY CANíT HUG IT OR EAT IT, IT ONLY FRUSTERATES THEM AND DOESNíT DO THEM MUCH GOOD. TO OTHERS ITíS STRONG AND DEPENDABLE, YOU CAN BUILD WITH IT, BUILD UPON IT, OR WORK WITH IT, ALSO USE IT TO SMASH PEOPLE IN THE FACE.Ē