SDI Advanced Ballistics (BBS 200) Practice Exam

The ignition of the priming mixture in a cartridge is primarily initiated by the mechanical action of the firing pin striking the primer, which creates a dent or indentation. This dent generates a localized pressure that is sufficient to compress the priming mixture within the primer. When this mixture is compressed, it becomes reactive, leading to its ignition.

The energy from the firing pin's strike effectively initiates the firing sequence by creating the necessary conditions for the primer to ignite. Once the primer is ignited, it then produces a flash that ignites the gunpowder in the cartridge, resulting in the expansion of gases that propel the bullet out of the casing.

Understanding this process is crucial, as it emphasizes the role of the firing pin in the ignition sequence, distinguishing it from other aspects of cartridge operation, such as the subsequent gas expansion or the pressure related to bullet seating, which occur after the initial ignition event.