NRA Ballistics & Ammunition 2

Question 1

What does 'FMJ' stand for and what is its primary design characteristic?

Accepted Answer

Full Metal Jacket — a bullet with a soft lead core enclosed in a harder metal shell

Answer

FMJ (Full Metal Jacket) bullets have a soft lead core enclosed in a harder metal (usually copper or gilding metal) jacket, which reduces barrel fouling and increases penetration.

Question 2

What is 'terminal ballistics'?

Accepted Answer

The study of how a projectile behaves upon impact with a target

Answer

Terminal ballistics examines what happens when a projectile strikes a target, including penetration, expansion, energy transfer, and wound channel formation.

Question 3

What is the key difference between a rimfire and a centerfire cartridge?

Accepted Answer

Rimfire cartridges have the primer compound in the rim of the case; centerfire cartridges have a separate primer in the center of the case head

Answer

In rimfire cartridges the priming compound is spun into the hollow rim of the case, while centerfire cartridges use a separate replaceable primer seated in the center of the case head.

Question 4

What is 'ballistic coefficient' (BC) and how does it affect bullet performance?

Accepted Answer

A numerical value describing a bullet's ability to overcome air resistance; higher BC means less velocity loss over distance

Answer

Ballistic coefficient is a measure of a bullet's ability to resist aerodynamic drag; a higher BC means the bullet retains velocity better over long distances.

Question 5

What causes 'keyholing,' and what does it indicate about the ammunition or firearm?

Accepted Answer

The bullet is too heavy for the barrel twist rate, causing it to tumble and strike the target sideways

Answer

Keyholing occurs when a bullet is insufficiently stabilized by the barrel's rifling twist rate and tumbles in flight, leaving an elongated key-shaped hole in the target instead of a round hole.

NRA - National Rifle Association Certified Instructor Practice Test

NRA - National Rifle Association Certified Instructor Practice Test

NRA Ballistics & Ammunition 2