What is the primary function of a case in ammunition?

The primary function of a case in ammunition is to serve as a container that holds all components together. It encapsulates the primer, propellant (gunpowder), and bullet, ensuring that these parts remain intact during handling and firing. The case is typically made of metal or plastic and is designed to withstand the pressures created when the propellant ignites.

In a functioning cartridge, the case plays a crucial role in maintaining the correct alignment and separation of each component, which is essential for reliable ignition and projectile performance. Its design also helps protect the propellant and primer from moisture and contamination, contributing to the overall effectiveness and safety of the ammunition.

While other choices describe elements related to ammunition, they do not accurately convey the role of the case. The explosive material (option B) refers to the primer, which ignites the propellant, not the case itself. The substance that creates pressure when burned (option C) pertains to the propellant, while the projectile expelled from a firearm (option D) directly refers to the bullet, which is contained within the case. Thus, the case's primary function is to provide a secure housing for all the components needed for firearm operation.