The "Bore Diameter" mark found on barrels of this era quite often do not reflect an "Exact" size. This gun when proofed would accept a plug gage having a size of 118.35 gauge (.340" but would not accept a plug gage of 108.49 gauge (.350"). This in metrics would translate to from 8.64mm to 8.89mm. Bores of this size are very commonly found o 9.3 mm chambered guns. My own later Drilling with a 9.3x72R chamber has a bore stamped 8.8mm (.3465")Most of these early 9.3 rifles had deep rifling or use with lead bullets, though mine is Nitro Proofed for use with a copper jacketed bullet.
