If you point a fake gun, water pistol or airsoft gun at a police officer expect to get shot. And an orange tip wont do anything to keep that from happenning. There is a kook in Tennessee who painted an orange tip to a firearm in an effort to provoke police....it did.
There is no Federal or Texas law that prohibits Duracoating a gun any color you want. In the last year I've transferred rasberry, billfold brown, lemon yellow, FDE, OD, pink and a dozen other colors....all perfectly legal.