[Kale]

It's interesting how even with metric 'labeled' cartridges you get odd numbers. What was the 7.92mm based on? Did some armorer have a random stick lying around and that happened to be the size he used for the bore of the prototype? I can understand 'customary' unit to metric conversions, which is where 7.62mm comes from, but is that always how non-integer metric calibers come to be?
Could be interesting as a campaign flavor detail: "bullet size was the diameter of the spear shaft of the first emperor's imperial guards" or something quirky like that.