If you slugged and measured the bore correctly, and it seems as if you did, it is of .323 bore; not of .318 bore. In a .323 bore, to shoot either .323 bullets or .318 bullets, both will work, but the .318 will not be as accurate as the tighter fitting .323 bullet. To shoot a .323 bullet in a .318 barrel causes increased pressures, and is to be avoided, so don't do it.