the ".30-30" came from: NBD od .308 (same as later .30-'06 Govt. caliber circa- 1906- go figure- the second "30" me from the dram equivalent of 30 grains of black powder in the newer smokeless power configuration. Load a spent .30-30 casing with 30 grains of a current nitro smokeless powder and you will exceed greatly the 45,000 psi chamber pressure rating of the 1894 Winchester--

"The field is the touchstone of the man"..