We aren't unitist when it comes to naming ammo. Half (ratio pulled from my ass) gets named based on US Customary units and half on Metric units. Most calibers get named in whatever unit sounds coolest. Seven point six two PRC (or any variation of the 7.62 verbalization) doesn't have the same ring or implied power as three hundred PRC.
I wait to the day the US rejects the metric completely, and invents a new system for Voltage measurement (proposed unit names: cell, shock, spark).
IIRC the US already uses metric (technically). The imperial units are defined in terms of metric units.
They're not serious before they stop using metric for ammunition
We aren't unitist when it comes to naming ammo. Half (ratio pulled from my ass) gets named based on US Customary units and half on Metric units. Most calibers get named in whatever unit sounds coolest. Seven point six two PRC (or any variation of the 7.62 verbalization) doesn't have the same ring or implied power as three hundred PRC.
I guess "9mm" really does sound a lot better than "almost 3/8 inch"
Which 9mm ammo?
If the common 9mm cartridge, 9x19 Parabellum, were designed in the US back in 1901 it would be a .38 caliber.
No idea, man, I'm European, I have no idea about ammo. I said 9mm because it's literally the only one I "know".