Oh Lord reeder, you done opened up a can of worms with American cartridge nomenclature which has no rhyme or reason that is redily discernalble to normal humans.
For your examples:
22-250 is a .22 caliber baised on the 250 Savage cartridge
30-06 The cartridge .30 caliber that was adopted by the US government in 1906
45-70 a .45 caliber cartridge the origonal loading of which was 70 grains of black powder
The first number is the nominal diameter usually. Of course there is the 38 (pistol) which is really 35.
The insanity goes on ad infinitum.
BCR
