GSI Ammunition & Ballistics Flashcards

What does 'grain' measure in the context of ammunition?

Answer: The weight of the bullet or powder charge

In ammunition, grain (gr) is a unit of weight used to measure bullet weight and powder charge; one pound equals 7,000 grains.

Which factor most directly affects bullet drop over long distances?

Answer: Gravity acting on the projectile during flight

Gravity continuously pulls the bullet downward during its flight, causing it to drop progressively more the farther it travels from the muzzle.

What is the difference between rimfire and centerfire ammunition?

Answer: Rimfire has the primer in the rim of the case; centerfire has a separate primer in the center of the base

Rimfire cartridges have priming compound distributed in the hollow rim of the case, while centerfire cartridges have a replaceable primer cup pressed into the center of the base.

Why is it important for a GSI instructor to teach students to match ammunition to the firearm's marked caliber?

Answer: To prevent dangerous chamber pressure spikes and potential firearm failure

Using ammunition that does not match the firearm's marked caliber can cause dangerously elevated chamber pressures, case ruptures, or catastrophic firearm failure.

What is the best practice when a student encounters a round that fails to fire after the trigger is pulled?

Answer: Keep the firearm pointed downrange for at least 30 seconds before carefully unloading (hangfire protocol)

A delayed firing (hangfire) can occur seconds after the primer is struck, so keeping the firearm pointed in a safe direction for at least 30 seconds prevents injury if it fires late.

Which type of bullet is typically recommended for practice and target shooting due to its cost and clean barrel performance?

Answer: Full metal jacket (FMJ)

Full metal jacket bullets have a complete metal casing over the lead core, making them affordable, feed reliably, and are widely used for range practice.