My 1913 drilling with a 9.3x72R rifle bbl is marked 8.8mm (.3465" while an 8x58 Sauer one with an 2,07 mark (I know they're not supposed to be dated prior to 1912 but this sure looks like a Feb 1907 date to me) is marked 172,28. As noted these gauge markings were in .010" increments so the 8.8mm would fall within the >.340"<.350" range of the 118/35 gauge.
The 172/28 gauge falls into a >.300"<.310" range & it uses the .318" bullet. These marks are all for the bore size, not including rifling. My two were both proofed for smokeless powser & jacketed bullets. I think that 8.7mm (.3425") is quite common on 9.3's proofed for lead bullets. I agree though, with an 118/35 bore even a .323" 8mm bullet should simply fall through the bore.
