NRA NRA Ammunition & Ballistics Fundamentals 1 — Questions and Answers
Question 1: What are the four basic components of a centerfire metallic cartridge?
- Case, primer, powder, bullet (Correct answer)
- Shell, cap, charge, projectile
- Brass, percussion cap, powder, slug
- Neck, head, primer, projectile
Correct 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.
Question 2: What distinguishes a rimfire cartridge from a centerfire cartridge?
- Rimfire uses a larger primer
- The priming compound is inside the rim of the case head (Correct answer)
- Rimfire cases are reloadable
- The bullet is seated below the case mouth
Correct 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.
Question 3: What is the purpose of the crimp on a cartridge?
- It increases bullet velocity
- It secures the bullet in the case and prevents movement during feeding (Correct answer)
- It centers the primer in the pocket
- It seals the case to prevent moisture
Correct 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.
Question 4: What does the term 'SAAMI' stand for and why is it relevant to gunsmiths?
- Society of American Arms & Munitions Industries — sets bore tolerances
- Sporting Arms and Ammunition Manufacturers' Institute — sets standardized cartridge and chamber specifications (Correct answer)
- Small Arms Ammunition Manufacturers Index — lists approved powders
- Standard American Armament and Manufacturing Institute — regulates barrel lengths
Correct 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.
Question 5: What is 'bullet setback' and why is it dangerous?
- When the bullet exits at an angle
- When the bullet is pushed deeper into the case, increasing chamber pressure (Correct answer)
- When the bullet fails to engage the rifling
- When the bullet is seated too far out causing feed failures
Correct 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.
Question 6: What is the function of a Boxer primer compared to a Berdan primer?
- Boxer uses two flash holes; Berdan uses one central flash hole
- Boxer has a single central flash hole and self-contained anvil; Berdan has two offset flash holes and uses the case anvil (Correct answer)
- They are identical in function and interchangeable
- Boxer primers are larger and used only in magnum cartridges
Correct 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.
NRA NRA Ammunition & Ballistics Fundamentals 1
What are the four basic components of a centerfire metallic cartridge?