NICHT FUR KUGEL" is NOT FOR BALL in German.
Some of these marks sound Hungarian, but then it should say "NEM GOLYONAK" instead of NICHT FUR KUGEL. Was Hungarian used in the proof during this period? Perhaps one of our european members can make sense of this.

From what you says is present, I can not find any indication of chamber length. The surest way is with a chamber gauge from Brownells. Though some here recommend using a mechanics ruler.

Pete