A metric unit of length. In firearms, it is most commonly used to name the caliber, in which case it refers to the diameter of the bore of the firearm. See the section on Naming of Calibers [yet to be written].
A metric unit of length. In firearms, it is most commonly used to name the caliber, in which case it refers to the diameter of the bore of the firearm. See the section on Naming of Calibers [yet to be written].