NRA Ballistics & Ammunition

Question 1

Which branch of ballistics studies the behavior of a projectile after it leaves the muzzle and before it reaches the target?

Accepted Answer

External ballistics

Answer

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?

Accepted Answer

The weight of a projectile or powder charge

Answer

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?

Accepted Answer

The distance from the bolt face to the point in the chamber that stops forward cartridge movement

Answer

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?

Accepted Answer

Insufficient powder or primer failure leaving the bullet lodged in the barrel, causing a potential obstruction

Answer

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?

Accepted Answer

The speed of the bullet as it exits the muzzle of the firearm

Answer

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.

NRA - National Rifle Association Certified Instructor Practice Test

NRA - National Rifle Association Certified Instructor Practice Test

NRA Ballistics & Ammunition