Ray Dobbins wrote- In general though, I don't think the guys who did the panto and cutting took the time to make the cuts and the lines so perfect that they "disappeared," as in this ring we are talking about.
Some notes from 30+ years ago, Art Stump complained that the stamped openings found on Record rings, (Nuovo Record in common conversation) were often off significantly, making pantographing problematic. He would often have to select a false center and diameter between each bolt hole to make a visually acceptable modification. His description was that Campagnolo was accurate where they needed to be and not elsewhere.
Crank arms even varied more along the non contact surfaces.
John Jorgensen
Torrance Ca