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

Full Magnum Jacketed — a high-pressure round with a reinforced case

Answer

Forward Metal Jacket — a bullet with extra weight at the front for stability

Answer

Fixed Metal Joint — a sealed primer that cannot be reloaded

Question 2

What is 'terminal ballistics'?

Accepted Answer

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

Answer

The study of how a bullet behaves inside the barrel during firing

Answer

The study of maximum range a bullet can travel

Answer

The study of bullet trajectory during its flight

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

Rimfire cartridges are larger in caliber than centerfire cartridges

Answer

Rimfire cartridges use smokeless powder while centerfire cartridges use black powder

Answer

Rimfire cartridges are reloadable while centerfire cartridges are not

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

A measure of how much a bullet expands upon impact, with higher values indicating greater expansion

Answer

A rating indicating the maximum safe chamber pressure for a given cartridge

Answer

The ratio of bullet weight to barrel twist rate required for stabilization

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

Excessive barrel heat is melting the bullet jacket, causing irregular impact patterns

Answer

The bullet is striking the target at a steep angle due to an obstructed sight line

Answer

A worn or damaged crown at the muzzle is causing the bullet to veer off course

Question 6

What is 'sectional density' (SD) and why is it important to hunters and instructors?

Accepted Answer

The ratio of a bullet's weight to the square of its diameter, indicating potential penetration capability

Answer

The ratio of a bullet's diameter to its length, used to determine optimal barrel twist rate

Answer

The measurement of how uniformly the bullet's core is distributed within the jacket

Answer

The ratio of powder charge weight to bullet weight, used to calculate maximum pressure

Question 7

What is 'overpressure' ammunition (indicated by '+P' or '+P+') and what precaution must an NRA instructor communicate to students?

Accepted Answer

'+P' ammunition is loaded to higher-than-standard pressure for increased velocity and must only be used in firearms rated for it

Answer

'+P' ammunition is loaded to lower-than-standard pressure for reduced recoil and is suitable for all firearms

Answer

'+P' ammunition uses a different primer type and is incompatible with standard firing pins

Answer

'+P' ammunition is a military designation meaning armor-piercing and is illegal for civilian use