Comment by W.B.lbl:
Subsequent to my first post here, I seem to have found U.S. manufacturers were using the metric system for pressing records, from the record contours to the die-cut labels and their holes. Before pressing, center labels pre-1937 were 75.0mm (2.9528"), shrunk by about 0.65%. (After '37, the label size in Bridgeport was extended to 76.5mm (3.0118"); the Hollywood plant still used the smaller size as of late 1939.)