But you don’t call it “point four five caliber” you call it “forty five caliber”. Similar is 7.62 mm AKA “thirty caliber”. It’s reasonable that someone wouldn’t know that it’s literally just hundredths of inches.
Shotgun gauge is wonky, so it’s not a given that the number would just be a diameter in units they are familiar with. “Grains” are also a meaningless unit to most people.
But you don’t call it “point four five caliber” you call it “forty five caliber”. Similar is 7.62 mm AKA “thirty caliber”. It’s reasonable that someone wouldn’t know that it’s literally just hundredths of inches.
Shotgun gauge is wonky, so it’s not a given that the number would just be a diameter in units they are familiar with. “Grains” are also a meaningless unit to most people.