" Quality rings don't need to be lapped, they are very high on quality control, not mass produced. "
Actually, the best machined rings in the world may have to be lapped if the receiver isn't straight, square, concentric, level from front to rear, etc. Show me a perfect receiver, especially on a factory rifle. I've seen more than 1 Remington receiver that could not be fitted with double dove-tail rings because the mounting holes were so far out of concentricity with the bore.