I can hear/feel rubbing while grinding on the Royal's finest settings.

On the Royal, we allow the two burrs (cone and ring) to touch and rub each other to allow you to come down to the finest grind; much finer than what you need for espresso. At finer grind settings, you may hear and/or feel a rub (at one side or all around), but it will not affect your grinder's performance or precision.