This drilling looks a lot like an early Sauer & Sohn, Suhl, predecessor of their models 30,32 to me. One of your photobucket pics seems to show a single Sauer trademark crown? If 148383 is a Sauer serial number, it too dates the gun to 1912. The gun seems to be heavily reworked and restocked to me, perhaps the original signatures were scrubbed off in the "restoration"? If it is a S&S product, the original chambering may have been indeed the proprietary 9.3x72R S&S Mike mentioned. But this S&S number was a blackpowder, lead bullet cartridge too, so without a proper reproof I would not use full power 9.3x74R factory loads in it. The problem here is not chamber wall thickness. Up to the 1920s the Suhl gunmakers used hi-temp brass brazing to assemble the chamber area of the barrels. This was ok for bp pressure cartridges, but sometimes the steel in the critical chamber area was "burned" and brittle. This was the reason for the design of such drilling cartridges like the 8x57R 360, 8x58R S&S, 8x72R Brenneke. For the innocent customer the "8mm" designations sounded the same as the then modern high power 8x57I or IR cartridges, but those "drilling" numbers were loaded to much lower pressures and ballistics. I have seen the sorry remains of an old drilling that was post-1990 rebored, rerifled and rechambered in Suhl from 6,5x58R S&S to 8x57IRS. The wall thicknesses appeared to be ok to all persons involved, the master gunsmith, the master barrelmaker and the proofhouse officials. At the proofhouse, on firing the prescribed 8x57IRS proofload, the chamber area blew apart. The breaks looked like coarse textured broken cast iron. It's the same problem like that with the low-numbered Springfields of the same time span: Most of them take lots of use and abuse, but some are brittle and may shatter if overstressed even slightly.
