What is the detonating mixture used to ignite the propellant or powder charge?

• A. Rim
• B. Primer
• C. Headstamp
• D. Bullet

Answer: (B)

The detonating mixture that starts the propellant burning is inside the primer. When the firing pin strikes, the primer’s small explosive composition detonates and creates a flame or shock that travels into the powder space, igniting the propellant. This ignition is what generates the rapid gas pressure needed to propel the bullet down the barrel.

Other terms don’t fit this role: the rim refers to a design feature in some cartridges, not the ignition composition; the headstamp is just markings on the base of the cartridge; the bullet is the projective that is ultimately propelled.