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.

(nutrition) Kilogram calorie or large calorie. A unit of energy 1000 times larger than the gram calorie. It is equivalent to the gram kilocalorie, approximately 4.2 kilojoules.

The gram calorie or small calorie, a non-SI unit of energy, equivalent to approximately 4.2 joules. This unit was widely used in chemistry and physics, being the amount of energy needed to raise the temperature of 1 gram of water by 1 °C.