.0355" difference between bore & groove dia's (.2835 (7.2mm) - .248) would be an awful lot. Is this a 7x57R, if so I would think bore size would have been no smaller than about .010-.012" at the very most, likely less as would have been for jacketed bullets. When you say "Old German" I would presume this gun would pre-date it being the proof date of Feb 1948. Of the two old drillings I have one is a pre-1912 & has the bore marked by the old gauge system & the other is from 1913 (9.3x72R) & has bore marked in mm's. I don't recall ever seeing a German rifle with bore marked in decimal inches, though they could exist.
