US Standard units don't match up most of the time either... We shoot 218 Bee, 219 Zipper, 220 swift, 221 Fireballs, 222 Rem, 223rem, 224 Valkyrie, and 225 Winchester, all with the same 0.224" bullets, not to mention all of the 2 digit monikers running around which truncate to simply "22" like 22 Nosler, Hornet, Rem Jet, 22-250, etc... So we have every thousandth of an inch for 8 thousandths incorporated into cartridge names... I have a dog named Major, a horse named Magnum, and had a dog named Tres... They're just names...