Here are a couple of close-ups for comparison:
(Note the added touches from my wife, as the the 4.5" is in the foyer).
Bright chrome – beer can caliber (the real steel beer cans)

Industrial hard chrome (Armaloy) – 4.55” bore (next to it are the zinc cannon balls, a candle-pin bowling ball and an iron sphere found near a foundery.

My pesonal feeling is that chrome is a bit much for a mortar, none of the two dozen or so I've made since these were chromed. What does one do when it gets scratched? If the tube is painted or in-the-white it's an easy restoration.