FMF Infantry Weapons Fundamentals 3 — Questions and Answers
Question 1: What is the effective casualty radius of the M67 fragmentation grenade?
- 5 meters
- 15 meters (Correct answer)
- 50 meters
- 100 meters
Correct answer: 15 meters
The M67 fragmentation grenade has an effective casualty radius of approximately 15 meters.
Question 2: When employing the M240B machine gun, what technique prevents barrel overheating during sustained fire?
- Firing in 100-round continuous bursts only
- Using controlled burst fire and conducting scheduled barrel changes (Correct answer)
- Pouring water over the barrel every 10 minutes
- Reducing the cyclic rate via the gas regulator to minimum setting
Correct answer: Using controlled burst fire and conducting scheduled barrel changes
The M240B gunner uses controlled burst fire and rotates spare barrels at regular intervals to manage heat and maintain effective fire.
Question 3: What is the purpose of the AN/PEQ-15 laser aiming device?
- Measure target range with sound waves
- Project visible and infrared laser beams for aiming and target designation (Correct answer)
- Illuminate targets with a white-light flashlight beam
- Provide GPS coordinates for fire missions
Correct answer: Project visible and infrared laser beams for aiming and target designation
The AN/PEQ-15 projects both visible and infrared laser beams, enabling accurate aiming in day and night operations when used with night vision devices.
Question 4: Which malfunction is characterized by a round that fails to eject after firing, leaving the spent case in the chamber?
- Failure to feed
- Stovepipe / failure to eject (Correct answer)
- Hangfire
- Squib load
Correct answer: Stovepipe / failure to eject
A stovepipe malfunction occurs when the spent case fails to fully eject and is caught by the bolt carrier group, protruding from the ejection port.
Question 5: What distinguishes a hangfire from a misfire?
- A misfire produces smoke; a hangfire produces no smoke
- A hangfire has a delayed ignition after trigger pull; a misfire has no ignition (Correct answer)
- A hangfire involves a squib; a misfire involves a dud
- There is no practical difference between the two
Correct answer: A hangfire has a delayed ignition after trigger pull; a misfire has no ignition
A hangfire involves a delayed but eventual firing of the round after trigger pull, while a misfire means the round fails to fire at all.
Question 6: The M72 LAW (Light Anti-Tank Weapon) is best described as:
- A reusable, shoulder-fired rocket system
- A disposable, pre-loaded single-shot rocket launcher (Correct answer)
- A crew-served recoilless rifle
- A wire-guided anti-tank missile
Correct answer: A disposable, pre-loaded single-shot rocket launcher
The M72 LAW is a lightweight, disposable, single-shot rocket launcher that is discarded after firing.
Question 7: What is the role of the rifleman's buddy system during immediate action drills?
- One Marine fires while the other reloads simultaneously on the same target
- Mutual security and assistance — one covers while the other clears a malfunction or reloads (Correct answer)
- Partners alternate firing at two separate targets independently
- One carries ammunition only while the other engages all targets
Correct answer: Mutual security and assistance — one covers while the other clears a malfunction or reloads
The buddy system ensures mutual support — one Marine maintains suppressive fire while the partner addresses a malfunction, reloads, or moves.
FMF Infantry Weapons Fundamentals 3
What is the effective casualty radius of the M67 fragmentation grenade?