The problem is, plastic or not, they are still BBs. If one should hit some random person in the eye you or your parents will be legally liable in any lawsuit and claim for medical damages. So while it might be legal it may not be wise.
It is not legal, I am an airsoft enthusiast, and you are publicly displaying weapons that may seem threatening to others around. Play in your backyard, better yet go to an airsoft field. You could hurt those around you, and you don't want that liability.