NRA Ammunition & Ballistics Flashcards

What is the significance of the headstamp on a cartridge case?

Answer: It identifies the manufacturer, caliber, and sometimes the year of manufacture

The headstamp is stamped on the base of the cartridge case and identifies the manufacturer, cartridge caliber, and sometimes additional information.

What is case annealing used for in ammunition reloading?

Answer: To soften the case neck and shoulder to restore ductility after repeated firing

Annealing uses controlled heat to soften brass case necks and shoulders that have become work-hardened from repeated firing and resizing, extending case life.

What does 'twist rate' refer to in a rifle barrel?

Answer: The rate at which the rifling rotates the bullet, expressed as one turn per X inches

Twist rate describes how quickly the rifling imparts spin to the bullet, expressed as the barrel length required for one complete bullet rotation (e.g., 1:10 means one turn in 10 inches).

What is the purpose of a wad in a shotgun shell?

Answer: To hold the shot together and seal propellant gases behind the shot column

The wad seals propellant gases behind the shot column for efficient energy transfer and cups the shot to reduce deformation as it travels down the barrel.

What is the purpose of a case crimp in pistol ammunition?

Answer: To prevent bullet setback and ensure consistent neck tension

Crimping the case mouth onto the bullet prevents bullet setback during feeding and ensures consistent neck tension for uniform ignition and velocity.

What is the term for the unburned or partially burned powder that exits the muzzle during firing?

Answer: Flash

The visible flash at the muzzle includes burning and unburned propellant gases; a muzzle flash device or suppressor can reduce this phenomenon.