Small arms terminology

Question 1

What are the three types of ballistics?

Answer 1

1. Internal
2. External
3. Terminal

Question 2

Breechblock

Answer 2

A component that seals the breech and blocks gases from the fired cartridge. (Bolts in rifles, slides in pistols).

Question 3

Disconnector

Answer 3

A device which prevents the firing of more than one round for one pull of the trigger OR prevents the weapon from being fired until the action is fully closed (in battery).

Question 4

Ejector

Answer 4

A cam or projection inside the receiver against which the cartridge case strikes and is thrown clear of the mechanism after it has been drawn from the chamber by the extractor.

Question 5

Extractor

Answer 5

A component that engages the rim or extractor groove of the cartridge case while the cartridge is in the chamber. After firing the extractor withdraws the case from the chamber when the action opens.

Question 6

Fluted chamber

Answer 6

Leaves linear burn marks on spent cartridge cases produced by the gases that cycle the weapon. Gases fill grooves in chamber, allowing for easier extraction of the spent cartridge case.

Question 7

Firing pin

Answer 7

The part of the firing mechanism that strikes or contacts the primer of the cartridge to cause ignition to fire the weapon.

Question 8

Headspace

Answer 8

The distance from the breechblock to the part of the chamber which stops the forward movement of the CARTRIDGE CASE.

Question 9

Muzzle break

Answer 9

A device at the muzzle end of the weapon which deflects the emerging powder gases. The energy imparted by this act of deflection pulls the weapon FORWARD to offset some of the rearward motion of recoil.

Question 10

Rifling

Answer 10

A series of spiral grooves in the bore of a barrel which imparts a spinning motion to the bullet as it travels the length of the barrel from the breech to the muzzle. Stabilizes the projectile in-flight.

Question 11

What are the five methods for creating rifling?

Answer 11

1. Cut rifling
2. Broached
3. Button
4. Hammer forging
5. Flow forming

Question 12

What are the two profiles for rifling?

Answer 12

1. Lands and grooves

2. Polygonal

Question 13

Sear

Answer 13

A component retained under spring tension that releases, by means of a trigger, either a firing pin, hammer, or bolt.

Question 14

Trigger

Answer 14

A finger actuated lever used to activate the firing mechanism, firing the weapon.

Question 15

Trigger bar

Answer 15

A connecting bar operating between the trigger and the sear. Nothing more than an extension of the trigger.

Question 16

Single action (SA)

Answer 16

Requires manual cocking (e.g. slide or hammer pulled rearward)

Question 17

Double action (DA)

Answer 17

The trigger bar cocks the weapon when the trigger is pulled and the sear releases the hammer when the trigger has reached maximum rearward movement.

Question 18

What are the five types of firing?

Answer 18

1. Single action (SA)
2. Double action (DA)
3. Semi-automatic only (semi-only)
4. Automatic-only (auto-only)
5. Selective fire (sel.-fire)

Question 19

Trajectory

Answer 19

The path the bullet takes from the muzzle of the weapon to the target. The bullet immediately begins to drop upon exiting the muzzle of the weapon due to atmospheric resistance and gravity.

Question 20

What are the two types of sights?

Answer 20

1. Fixed

2. Adjustable

Question 21

How does the US military measure rounds?

Answer 21

By taking the diameter of the bullet by the length of the cartridge case, in millimeters (e.g. 7.62 x 51mm).

Question 22

How does the civilian sector measure rounds?

Answer 22

Caliber calculated by taking the distance across the bore of the weapon, measured from land-to-land, expressed in hundredths of an inch.

Question 23

What are the three parts of trajectory?

Answer 23

1. Rising branch
2. Maximum ordinate
3. Falling branch

Question 24

What is a battle sight?

Answer 24

The range that allows the shooter to hit a target between the throat and waist without a sight adjustment. Exact range varies with weapon and caliber.

Question 25

Flash suppressor

Answer 25

A three or four pronged device attached to the muzzle of a weapon, designed to cool the hot gases as they leave the muzzle behind the round; cooling gases reduces the muzzle flash.

Question 26

Choke

Answer 26

Constriction at the muzzle end of the barrel that condenses the shot pattern to increase the max effective range.

Question 27

Ballistics

Answer 27

The science and study of the motion and impact of projectiles.