I have a beautiful Starrett 0-6" (0-150mm) micrometer set, carbide faces, that my grandfather purchased before either of you were born, because AMERICA WOULD BE METRIC. Apparently all the nazi's designing our rockets still designed everything in Metric, and NASA decided that everything would be metric. The company my grandfather worked at did a lot of US Govt work, and NASA was shocked at the quotes they were getting back. That was because the companies had to pay their draftsman to redraw all the prints, so all the workers could machine the parts, in inch, on their machines which were inch.
My grandfather was and still is the only person I have ever met who could convert inch to metric in his head, along with most trig and what not on the fly. He always chuckled at me pulling out a calculator to convert.
Along I came and served my apprenticeship at a metric shop. I was bi-lingual. He pulled out these NOS micrometers, with the packing grease still on the spindles, and sold them to me for what he paid brand new nearly 50 years before.
Irrelevant anecdote, but I still use those mics, and I cherish them just as much as anything in his Gerstner, whether it is Starrett or Lufkin, inch or metric.
"The U.S.A. received copies of the Imperial Standard Yard in 1856, but in 1890 they acquired thre platinum-iridium Prototype Metres (Nos. 12, 21, amd 27) and decided to adopt Prorotype No. 27 as the U.S. Primary Standard of Length, the Metre Standard having proved itself to be of better stability than the Yard Standard." - p9 Jig Boring, Connell