Understood - but do you actually SAY “point twenty-two caliber” when referring to a twenty-two, or do you say “Twenty-two caliber”?
The 2 mm Kolibri (also known as the 2.7 mm Kolibri Car Pistol or 2.7×9 mm Kolibri) is the smallest commercially available centerfire cartridge. It’s half the size of a twenty-two caliber. (.11 inch)