NRA NRA Firearm Mechanisms & Action Types 2 — Questions and Answers
Question 1: What is the primary role of the recoil spring in a semi-automatic pistol?
- It returns the slide to battery and absorbs recoil energy (Correct answer)
- It drives the firing pin forward
- It holds the magazine in place
- It controls the trigger pull weight
Correct answer: It returns the slide to battery and absorbs recoil energy
The recoil spring stores energy as the slide moves rearward and returns the slide forward to chamber the next round.
Question 2: In a double-action/single-action (DA/SA) pistol, what happens on the first trigger pull?
- Only the sear is released
- The trigger both cocks and releases the hammer (Correct answer)
- The safety is automatically disengaged
- The slide moves rearward to chamber a round
Correct answer: The trigger both cocks and releases the hammer
On the first DA pull, the trigger performs two actions — cocking the hammer and releasing it — resulting in a longer, heavier pull.
Question 3: What is headspace in a firearm?
- The gap between the front sight and the rear sight
- The distance from the bolt face to the datum line in the chamber (Correct answer)
- The clearance between the barrel and the slide
- The space inside the magazine above the top round
Correct answer: The distance from the bolt face to the datum line in the chamber
Headspace is the critical measurement from the bolt face to the point where the cartridge is stopped in the chamber.
Question 4: Which part of a revolver rotates to align each chamber with the barrel?
- The frame
- The cylinder (Correct answer)
- The crane
- The yoke
Correct answer: The cylinder
The cylinder rotates with each trigger pull or hammer cock to index a new chamber in line with the barrel.
Question 5: What is the purpose of a firing pin block (drop safety)?
- It prevents the firing pin from moving unless the trigger is deliberately pulled (Correct answer)
- It stops the hammer from striking the primer twice
- It keeps the firing pin centered in the bolt
- It prevents the extractor from damaging the case rim
Correct answer: It prevents the firing pin from moving unless the trigger is deliberately pulled
A firing pin block prevents accidental discharge if the firearm is dropped by blocking the firing pin unless the trigger is fully depressed.
Question 6: In a gas-operated semi-automatic rifle, where is propellant gas typically tapped to cycle the action?
- At the chamber
- Near the muzzle end of the barrel
- From a port in the barrel forward of the chamber (Correct answer)
- Through the ejection port
Correct answer: From a port in the barrel forward of the chamber
Gas is tapped from a port drilled in the barrel, typically several inches forward of the chamber, to drive the bolt carrier rearward.
NRA NRA Firearm Mechanisms & Action Types 2
What is the primary role of the recoil spring in a semi-automatic pistol?