New Guy with 1918 Erfurt Luger

[refab60]

Hi!
I don't want to open a new tread so I post here.
I'm a new follower too - from Italy, and also I have my first Luger.
The "32" is marked on all parts but the magazine (it has a 4 number but I'm able to read them). Reflushed? What's the groove on the chamber, just before the barrel, for?
Do any tried to shoot a 25metr target? I tried but it was a disaster: bullets flying everywhere and 16" low.
As soon as possible I'll post more detailed pictures.