CRFSC Major Parts and Actions 5 — Questions and Answers
Question 1: What is the function of the gas port drilled through the barrel of a gas-operated semi-automatic firearm?
- It vents excess pressure to prevent over-pressure damage to the action
- It allows a measured amount of propellant gas to be tapped off to cycle the action (Correct answer)
- It improves accuracy by equalizing pressure around the bullet
- It reduces fouling by allowing carbon deposits to escape the barrel
Correct answer: It allows a measured amount of propellant gas to be tapped off to cycle the action
The gas port is a small hole drilled into the barrel at a calculated distance from the chamber; propellant gas enters here and is directed to operate the action (via a piston or gas tube) after the bullet passes the port.
Question 2: Which part of the trigger group is responsible for resetting the trigger to a fireable position after each shot in a semi-automatic firearm?
- The hammer spring (mainspring)
- The trigger return spring (Correct answer)
- The sear spring
- The disconnector spring
Correct answer: The trigger return spring
The trigger return spring pushes the trigger forward after each shot, resetting it to its original position so the next trigger pull can engage the sear and fire the weapon.
Question 3: On a revolver, what is the purpose of the hand (also called the pawl)?
- It holds the cylinder closed against the barrel forcing cone
- It rotates the cylinder one position each time the hammer is cocked or the trigger is pulled (Correct answer)
- It locks the cylinder in alignment with the barrel when the hammer falls
- It extracts spent cases when the ejector rod is pressed
Correct answer: It rotates the cylinder one position each time the hammer is cocked or the trigger is pulled
The hand is a small lever attached to the hammer or trigger that engages the cylinder ratchet and advances the cylinder one chamber per trigger or hammer cycle.
Question 4: What is the primary difference between a fixed barrel and a tilting/dropping barrel in a semi-automatic pistol?
- Fixed barrels are more accurate because the barrel never moves during cycling; tilting barrels move to unlock from the slide during recoil (Correct answer)
- Fixed barrels are found only on revolvers; tilting barrels are found only on single-action pistols
- Fixed barrels require a stronger recoil spring; tilting barrels operate by gas pressure
- Fixed barrels use a rotating bolt; tilting barrels use a straight blowback system
Correct answer: Fixed barrels are more accurate because the barrel never moves during cycling; tilting barrels move to unlock from the slide during recoil
A fixed barrel (common in blowback designs) remains stationary, while a tilting/dropping barrel (Browning-style) cams downward to unlock from the slide during the rearward recoil stroke, allowing the action to cycle.
Question 5: What does the term 'action' refer to when describing a firearm?
- The trigger pull weight required to fire the firearm
- The mechanical assembly that loads, fires, extracts, and ejects cartridges (Correct answer)
- The speed at which the firearm cycles between shots
- The legal classification of the firearm under the Criminal Code
Correct answer: The mechanical assembly that loads, fires, extracts, and ejects cartridges
The action is the complete mechanical system — including the bolt, trigger group, extractor, and ejector — that performs the cycle of operations: feed, chamber, lock, fire, unlock, extract, and eject.
Question 6: What is a 'free-floating' barrel, and why is it used on target and precision rifles?
- A barrel that can be removed without tools for easy cleaning
- A barrel that contacts only the receiver and does not touch the stock at any other point, preventing pressure-induced accuracy shifts (Correct answer)
- A barrel with no fixed sights, allowing any optic to be mounted
- A barrel treated with a friction-reducing coating to improve bullet velocity
Correct answer: A barrel that contacts only the receiver and does not touch the stock at any other point, preventing pressure-induced accuracy shifts
A free-floating barrel is bedded only at the receiver and clears the stock along its entire length, so inconsistent hand pressure, sling tension, or stock swelling cannot deflect the barrel and affect point of impact.
Question 7: What is the purpose of the magazine well (mag well) on a semi-automatic firearm?
- It stores extra cartridges internally as a backup to the detachable magazine
- It is the opening in the frame or receiver that accepts and guides the magazine into its seated position (Correct answer)
- It houses the trigger group components to protect them from debris
- It allows the shooter to check the round count without removing the magazine
Correct answer: It is the opening in the frame or receiver that accepts and guides the magazine into its seated position
The magazine well is a precisely machined opening in the frame or lower receiver that accepts the magazine and aligns it so the top round presents correctly for feeding into the chamber.
CRFSC Major Parts and Actions 5
What is the function of the gas port drilled through the barrel of a gas-operated semi-automatic firearm?