My 1913 drilling with a 9.3x72R rifle bbl is marked 8.8mm (.3465" while an 8x58 Sauer one with an 2,07 mark (I know they're not supposed to be dated prior to 1912 but this sure looks like a Feb 1907 date to me) is marked 172,28.
2-piper:
Some sources give Suhl as officially commencing tube dating in 1923, but there are some examples prior to that. Suhl, which was set ablaze by Imperial Croats in the 1630s, was re-established in 1891/1893 but there were other exiting proofhouses. Most, but not all, target arms have tube dating beginning around the turn of the 20th Century. So, it isn't all that odd to see a date say from 1903 on. The plug gauge notation ceased circa 1910, although there are some target longarm examples until at least 1911, and the numeric stamp began.
Kind Regards,
Raimey
rse
