NRA NRA Ammunition & Ballistics Fundamentals 2 — Questions and Answers
Question 1: What is 'terminal ballistics'?
- The study of a bullet's flight path through the air
- The study of what happens when a bullet strikes and interacts with a target (Correct answer)
- The measurement of muzzle velocity
- The analysis of chamber pressure curves
Correct answer: The study of what happens when a bullet strikes and interacts with a target
Terminal ballistics describes bullet behavior upon impact, including expansion, penetration, and energy transfer.
Question 2: What is 'muzzle velocity' and how does it typically affect bullet trajectory?
- The speed of the bullet at 100 yards — higher velocity means more drop
- The speed of the bullet as it leaves the muzzle — higher velocity generally produces a flatter trajectory (Correct answer)
- The rotational speed imparted by rifling — measured in RPM
- The speed of the expanding gas at the muzzle — unrelated to bullet path
Correct answer: The speed of the bullet as it leaves the muzzle — higher velocity generally produces a flatter trajectory
Muzzle velocity is the bullet's speed at the barrel's muzzle; higher velocity reduces trajectory drop over a given distance.
Question 3: What is 'chamber pressure' and how is it typically measured in the US?
- The force of the bolt closing — measured in foot-pounds
- The peak pressure generated by burning propellant — measured in PSI or CUP (Correct answer)
- The atmospheric pressure inside the chamber before firing — measured in bar
- The pressure needed to extract the case — measured in pounds of force
Correct answer: The peak pressure generated by burning propellant — measured in PSI or CUP
Chamber pressure is the peak gas pressure generated when propellant burns, measured in PSI (pounds per square inch) or CUP (Copper Units of Pressure).
Question 4: What does 'ballistic coefficient' (BC) measure?
- The amount of propellant needed to achieve a given velocity
- A bullet's ability to overcome air resistance and retain velocity in flight (Correct answer)
- The ratio of bullet weight to bore diameter
- The coefficient of friction between the bullet and rifling
Correct answer: A bullet's ability to overcome air resistance and retain velocity in flight
Ballistic coefficient quantifies how efficiently a bullet overcomes air drag — a higher BC means less velocity loss and less wind drift over distance.
Question 5: What is the difference between 'jacketed' and 'lead' bullets?
- Jacketed bullets are made entirely of copper; lead bullets are purely aluminum
- Jacketed bullets have a lead core encased in a harder metal jacket; lead bullets are cast from pure or alloy lead (Correct answer)
- Jacketed bullets are only used in rifles; lead bullets are only used in handguns
- They are the same except jacketed bullets have a polymer tip
Correct answer: Jacketed bullets have a lead core encased in a harder metal jacket; lead bullets are cast from pure or alloy lead
Jacketed bullets wrap a lead or alloy core in a gilding metal or copper jacket, reducing barrel fouling and allowing higher velocities.
Question 6: What is 'over-pressure' ammunition (denoted +P or +P+) and what should a gunsmith verify before use?
- +P is standard-pressure ammo with a polymer coating — no special verification needed
- +P ammunition is loaded to higher-than-standard pressure — verify the firearm is rated for it by the manufacturer (Correct answer)
- +P means the primer is magnum-rated — safe in all modern firearms
- +P+ is a military designation for tracer rounds only
Correct answer: +P ammunition is loaded to higher-than-standard pressure — verify the firearm is rated for it by the manufacturer
+P and +P+ ammunition operates at elevated pressures and should only be used in firearms specifically rated for it to avoid accelerated wear or damage.
NRA NRA Ammunition & Ballistics Fundamentals 2
What is 'terminal ballistics'?