What is the definition of a cartridge in firearms?

A cartridge is defined as a fully assembled round that includes all necessary components to be fired from a firearm. This typically consists of the bullet (projectile), the propellant (gunpowder), and the primer all contained within a casing. Understanding this definition is crucial for firearm operation and safety, as it highlights the importance of each component working together to ensure proper function when the trigger is pulled.

The other choices do not encompass the complete definition of a cartridge. A bullet alone refers only to the projectile, while an empty shell casing is just the part that holds the propellant and primer once the bullet has been fired. A type of firearm does not relate to a cartridge but rather identifies a specific weapon used to fire cartridges. Thus, recognizing a cartridge as a fully assembled round is essential for anyone involved in firearms training or operations.