Study Identifying Luger Caliber: .30 Luger or 9mm Luger?

[cirelaw]

Up until 1908 with the exception of the commercial fat barrel 1902, 7.65 including the Swiss was the only calibre that I am aware! All the 1908 models Army, Commercial and Military were the 9mm. A few 1920 carbines retained the smaller calibre 7.65. as many used leftover parts during the Weimer era~