Small Arms Terminology Trivia Quiz

Answer: Axis of the bore

The axis of the bore is a line through and parallel to the center of the bore. The bore is the inside of the barrel.

Answer: Chamber Throat

The chamber throat can also be referred to as the leade or forcing cone in a shotgun.

Answer: Compensator

High-powered firearms jump when fired. Automatic firearms will climb and move in the direction of rifling twist when fired. A compensator vents some of the propellant gases in an upwards and sideways direction to dampen the effect. Flash suppressors don't have a direction-imparting force, they are vented the whole circumference of the barrel. Buffers slow rearward movement of the recoiling parts.

Answer: Disconnector

The disconnector directly or indirectly retains the hammer in the cocked position after firing so as to interrupt the cycle of operation, and prevent automatic firing.

Answer: Firing Pin

The firing pin can also be called a hammer nose if it is integral to the hammer, or a striker if it does not operate in line with the axis of the bore.

Answer: Gauge

Gauge measurement is the number of round lead balls of bore diameter that equal one pound. 12 Gauge is the diameter of one lead ball that weighs 1/12 lb.

Answer: Headspace

Proper headspacing is a critical measurement that is vital to the safe operation of a firearm. Improper headspacing can cause the breech locking mechanism to malfunction, and can lead to an explosion of the breech, causing serious injury or death.

Answer: Blowback

A blowback action allows a totally unlocked breech on firing, and relies simply on the mass of the breech block, the strength of the return spring, and the recoil energy of the fired cartridge to cycle the action. Blowback actions are commonly found in pistols and low-powered rifles.

Answer: Sear

The sear is what holds the hammer in the cocked position, and is either indirectly or directly disengaged when the trigger is pulled to fire the cartridge.

Answer: Rifling

Rifling was invented in the middle ages. It can be uniform (rate of twist remains constant from the chamber to the muzzle) or progressive (rate of twist increases at the muzzle end). Progressive twists are commonly found in artillery and other arms with short barrels. It acts like an accelerator for the projectile.

Answer: Locked

Locked is the condition in which the breech block is solidly secured in a fixed relationship to the chamber in such a means so as to prevent blowback. Also known as "In-Battery".

Answer: Muzzle Brake

A muzzle brake is often found on high-powered rifles where accuracy is paramount. Sniper rifles are a good example, as recoil can cause the rifle to pull when firing - and miss the target.

Answer: Obturation

Rearward obturation is usually provided by the soft cartridge brass expanding against the chamber wall. Forward obturation is provided by the projectile being a slightly larger diameter than the bore (two or three thousandths of an inch).

Answer: Cartridge Case Head Clearance

Proper cartridge case head clearance is combined with proper firing pin protrusion to ensure reliable firing of a weapon. It is commonly confused with headspace.

Answer: Ballistics

Ballistics is the study of a flying object. It can be divided into four categories:

Internal Ballistics - Studies the projectile from chamber to exiting the bore.
Intermediate Ballistics - Studies the projectile from the moment it leaves the muzzle to the moment it reaches maximum stability.
External Ballistics - Studies the projectile from the point of maximum stability to the point of impact.
Terminal Ballistics - Studies the projectile from the moment of impact to the cessation of flight and travel.