NRA Ammunition & Ballistics Fundamentals Flashcards

What are the four basic components of a centerfire metallic cartridge?

Answer: Case, primer, powder, bullet

A centerfire cartridge consists of a brass (or other metal) case, a primer seated in the case head, propellant powder, and a bullet.

What distinguishes a rimfire cartridge from a centerfire cartridge?

Answer: The priming compound is inside the rim of the case head

In rimfire cartridges, the priming compound is spun into the hollow rim of the case, struck by the firing pin at the rim rather than a central primer.

What is the purpose of the crimp on a cartridge?

Answer: It secures the bullet in the case and prevents movement during feeding

Crimping folds or rolls the case mouth into a cannelure or against the bullet to prevent bullet setback during feeding and handling.

What does the term 'SAAMI' stand for and why is it relevant to gunsmiths?

Answer: Sporting Arms and Ammunition Manufacturers' Institute — sets standardized cartridge and chamber specifications

SAAMI establishes standardized dimensions and pressure limits for cartridges and chambers, ensuring safe interchangeability.

What is 'bullet setback' and why is it dangerous?

Answer: When the bullet is pushed deeper into the case, increasing chamber pressure

Bullet setback reduces case volume, raising pressure to potentially dangerous levels that can cause case failure or damage the firearm.

What is the function of a Boxer primer compared to a Berdan primer?

Answer: Boxer has a single central flash hole and self-contained anvil; Berdan has two offset flash holes and uses the case anvil

Boxer primers contain their own anvil and seat over a single central flash hole, making the case easy to deprime and reload; Berdan primers rely on an anvil in the case.