I had a chamber cast done of a Vinzenz Urbas, (Ferlach), Drilling made 1927 according to proof marks.
I don't think there is a rifle calibre stamped anywhere.
The chamber best matches a straight-taper 8x58R Sauer case, but it has a very distinct shoulder, (the Sauer round does not). It does not seem to exactly match anything, for instance, any of the "mit Rand" cases listed in the RWS publication Wiederladen (1. Auflage).
It's too big to be an 8x57R350 and not big enough to be a 8x57JR. The rim diameter and base diameter match closely an 8x58R Sauer. But it's not a .303 British, or Savage or anything of that vintage that I can identify, thought it looks like the British round. The gun came from Switzerland, (might be a clue!).
R1 (rim diameter), .504" / 12.802mm
P1 (base diameter), .438" / 11.1252mm
P2 (shoulder diameter), .386" / 9.804mm
H2 (neck diameter at mouth), .343" / 8.712mm
L3 (overall case length), could be either:
2.186" / 55.5mm
or 2.360" / 60.0mm, (there are 2 similar marks on the casting)
The neck is either .270" / 6.858mm or .435" / 11.049mm long.
The bore is .317" according to my gunsmith. The cast measures .318" now. (4 groove).
Any suggestions much appreciated.
