caliber

Diameter of the bore of a firearm, typically measured between opposite lands.

The diameter of round or cylindrical body, as of a bullet, a projectile, or a column.

A nominal name for a cartridge type, which may not exactly indicate its true size and may include other measurements such as cartridge length or black powder capacity. Eg 7.62×39 or 38.40.

Unit of measure used to express the length of the bore of a weapon. The number of calibres is determined by dividing the length of the bore of the weapon, from the breech face of the tube to the muzzle, by the diameter of its bore. A gun tu

Relative size, importance, magnitude.

A snort of about the calibre of an explosion in an ammunition dump escaped my late father's sister.