Question: How can I tell if the bores of my over and under shotgun are chrome-plated?
Answer: First clean the bore thoroughly to remove all traces of oil, solvent or fouling. Next take a good cold blue and using a Q-tip, apply a drop of the cold blue to the surface of the bore at a point where you can easily see it. I usually do this near the muzzle. If the bore is chrome-plated, the cold blue will have no effect on the steel; it will not color the metal. If, on the other hand, the bore is not plated; the cold blue should darken or discolor the steel.
By the way, some manufacturers such as Browning will chrome plate the chamber but not the bore on some shotguns. To check the bore, be sure to actually conduct the cold blue test in the bore and not in the chamber.