1916 Dwm 7.65

[A.Mifsin]

Luger continued to market and demonstrate his guns, but many army commissions had doubts about the stopping power of the small round. Luger thus redesigned the round, doing away with the necked design (originally conceived as an effective gas seal) and created the 9mm parabellum (or 9 millimeter luger) round. The slightly tapered case together with a machined step in the pistol's chamber created an equally effective gas seal.
--------------------------

Thank you all you guys, you are very kind with your information, but as G.van Vlimmeren said as above it seems that it is not only a question of changing the barrel, since the chamber is different from a 9mm to 7.65mm.
So, one canâ??t simply change the barrel and as John said, it is an expert job (maybe some day someone will explain how it is done, sort of the tricks of the trade:-) sending a Luger out of my country and getting it back modified, is a nightmare) but you have to modify the chamber also. I am saying this because as far as I know the 9mm round rest on the edge of the front cartridge, and the 7.65mm rest on the neck of the cartridge in the chamber.
I canâ??t see why someone change a 9mm Luger barrel to 7.65mm if not as Vlimmeren said because of restriction in his country.
Thank you all for your help
Alf