NRA Ballistics & Ammunition 1 — Questions and Answers
Question 1: Which branch of ballistics studies the behavior of a projectile after it leaves the muzzle and before it reaches the target?
- Internal ballistics
- External ballistics (Correct answer)
- Terminal ballistics
- Wound ballistics
Correct answer: External ballistics
External ballistics covers the projectile's flight path from muzzle to target, including factors like gravity, wind, and air resistance.
Question 2: In ammunition terminology, what does 'grain' measure?
- The length of the cartridge case
- The weight of a projectile or powder charge (Correct answer)
- The diameter of the bullet
- The pressure generated by ignition
Correct answer: The weight of a projectile or powder charge
Grain (gr) is a unit of weight equal to 1/7,000 of a pound, used to measure both bullet weight and powder charge weight.
Question 3: What is 'headspace' in firearm and ammunition terminology?
- The distance between the front sight and the rear sight
- The gap between the trigger and the trigger guard
- The distance from the bolt face to the point in the chamber that stops forward cartridge movement (Correct answer)
- The space inside the magazine above the top round
Correct answer: The distance from the bolt face to the point in the chamber that stops forward cartridge movement
Headspace is the distance from the bolt face to the datum line in the chamber that stops the cartridge from moving forward; incorrect headspace can cause dangerous malfunctions.
Question 4: What causes a 'squib load' and why is it dangerous?
- Excessive powder charge that generates dangerously high pressure
- Insufficient powder or primer failure leaving the bullet lodged in the barrel, causing a potential obstruction (Correct answer)
- A cartridge loaded with the wrong caliber bullet
- A primer that ignites late after the trigger is pulled
Correct answer: Insufficient powder or primer failure leaving the bullet lodged in the barrel, causing a potential obstruction
A squib load occurs when insufficient powder or a defective primer fails to fully propel the bullet, leaving it stuck in the barrel; firing another round into an obstructed barrel can cause catastrophic failure.
Question 5: What is 'muzzle velocity' as it applies to ammunition performance?
- The rotational speed of the bullet as it travels downrange
- The speed of the bullet as it exits the muzzle of the firearm (Correct answer)
- The rate at which the powder charge burns inside the case
- The velocity at which the bullet impacts the target
Correct answer: The speed of the bullet as it exits the muzzle of the firearm
Muzzle velocity is the speed of the projectile at the moment it leaves the barrel, typically measured in feet per second (fps), and is a key factor in external ballistics.
Question 6: Which of the following best describes a 'sabot' round?
- A bullet coated with a lubricant to reduce barrel friction
- A sub-caliber projectile housed in a carrier that is discarded after leaving the muzzle (Correct answer)
- A bullet designed to expand upon impact with the target
- A cartridge loaded with multiple small projectiles
Correct answer: A sub-caliber projectile housed in a carrier that is discarded after leaving the muzzle
A sabot is a sleeve or carrier that allows a smaller-diameter projectile to be fired from a larger-bore barrel; the sabot falls away after the bullet exits the muzzle.
Question 7: What are the four components of a standard centerfire cartridge?
- Primer, case, powder, and wad
- Case, bullet, powder, and primer (Correct answer)
- Bullet, jacket, core, and propellant
- Shell, powder, slug, and cap
Correct answer: Case, bullet, powder, and primer
A centerfire cartridge consists of the case (brass), bullet (projectile), powder (propellant), and primer (ignition source).
NRA Ballistics & Ammunition 1
Which branch of ballistics studies the behavior of a projectile after it leaves the muzzle and before it reaches the target?