Colt furniture will become shiny with use. It is typically dull and dry, almost grey when new.
I find it slightly ammusing when guys pass up on exceptional condition USGI furniture because it isn't shiny.... Slightly annoying when selling it, but good to go when buying!
Early Colt A2 hand guards do not have the "do not remove" warning on inside of hand guards, later are marked, I have seen a couple variations.