Actually the orange tip only applies to import, commercial sale, and transport in commerce. Once a private individual purchases the gun it's perfectly legal for them to remove the tip as far as Fed. law is concerned. I personally remove the tips on my guns and replace them with regular black flash hiders. That orange tip looks so goofy.
I don't mind Airsoft guns (i.e. replica guns), but I have concerns about the orange tip. One one hand, it's good to help distinguish a real firearm from a replica. On the other hand, I can see where thugs could start painting the tips of their real guns orange so they can openly carry them around without anyone questioning.