https://de.wikisource.org/wiki/Bekanntmachung,_betreffend_die_Ausf%C3%BChrung_des_Gesetzes_%C3%BCber_die_Pr%C3%BCfung_der_L%C3%A4ufe_und_Verschl%C3%BCsse_der_Handfeuerwaffen

91/83(9,40mm) plug gauge which would pair w/ that 1903 Z-M date then mm stamps may be from a proof effort @ Suhl prior to 1912.


Cheers,

Raimey
rse