NRA Firearm Mechanics & Operation Flashcards

What is the primary function of the recoil spring in a semi-automatic pistol?

Answer: To return the slide forward and absorb recoil energy

The recoil spring absorbs the energy of the slide moving rearward and then drives the slide back into battery.

What is the term for the condition when a firearm's bolt or slide is fully forward and locked into battery?

Answer: In battery

A firearm is said to be 'in battery' when the bolt or slide is fully forward and the action is locked, ready to fire.

What determines the lock time of a firearm?

Answer: The time from trigger release to primer ignition

Lock time is the elapsed time between trigger release and primer ignition, influenced by firing pin weight and spring tension.

What is the function of the gas port in a gas-operated semi-automatic rifle?

Answer: To bleed propellant gas to cycle the action

The gas port allows a portion of propellant gas to bleed off from the barrel and redirect it to operate the bolt carrier group.

In a bolt-action rifle, what is the purpose of the locking lugs?

Answer: To lock the bolt securely against the receiver to contain chamber pressure

Locking lugs engage recesses in the receiver to securely lock the bolt in place, safely containing the high pressures generated during firing.

What is the purpose of the ejector in a firearm?

Answer: To kick the spent case clear of the action after extraction

After the extractor pulls the spent case from the chamber, the ejector strikes it to fling it clear of the action.