The first screw machines they bought were from the UK, at least that is what I read.
Whitworth predates "standardized" metric pitches, IIRC.
The luger screws and threads are a hybrid, metric diameters and TPI. Whitworth is a 55 degree angle thread, the current standard is 60 degrees, so depending on the use/tolerance/number of threads, a 30 TPI Whitworth will "fit"(close enough) a 30 TPI modern thread.
Changing the gearing from TPI to metric is a bear and old "english system" lathes just won't do it.
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03man(Don Voigt); Luger student and collector.
Looking for DWM side plate: 69 ; Dreyse 1907 pistol K.S. Gendarmerie
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