I often see the date 1905 and Otto Bock's name associated with the introduction of the 9.3X62, but "sometime in the 1900s" for the 9.3X74R. Has anyone ever heard precisely when and where the latter was introduced and by whom?

Bill if no one can tell you here, I can't, try posting in the European section, some one there may be able to help.
Members there were able to date the 9.3x64.
Good luck.

The year of introduction was 1902 in Germany.

There was a 9.3x74.7R that was produced by DWM in 1900 with the DWM number of 474. The 9.3x74R as we know it today was given the DWM number 474A in 1902 and based on a different parent case to the 9.3x74.7R

The designer is not known.

Gerard: Thanks.