It experienced preliminary proof in Ferlach in 1931 and was completed in 1932 as Jani notes. A chamber cast would be best but the length of the chamber might narrow the field. 6.5X48R, 6.5X58R, 6.5X65R & 6.5X70R are just a few. For a wild guess, I'd choose the 6.5X70R, as that seemed to be an Austrian favorite and then there's the 6.5X65R S&S. Is the Sirius scope a Modell G? I believe the mounts are see thru Austrian. I don't think the 6 surmounted by the tilde to pair with the 6.7mm. Also the stamp of the "C"s back to back is common on tubesets.
Kind Regards,
Raimey
rse
