Terms

Question 1

Breech

Answer 1

The outside, rear face of the barrel which meets the face of the bolt or breechblock

Question 2

Breechblock

Answer 2

The component that seals the breech and blocks gases from the fired cartridge from exiting to the rear of the chamber.
Bolts in rifles and MG’s.
Inside of the slide in pistols.

Question 3

Cartridge

Answer 3

Consists of the cartridge case and the bullet.

Question 4

Headspace

Answer 4

The distance from the breechblock to the part of the chamber that stops the forward movement of the cartridge case.

All Weapons have headspace.

Question 5

Three Ways to Measure Headspace

Answer 5

Slide Face- Pistol
Rimmed Case- PKM
Rimless Case- M4

Question 6

Types of Headspace Gauges

Answer 6

Go Gauge
No Go Gauge
Field Gauge

Question 7

Go Gauge

Answer 7

This gauge will fit the weapon’s headspace and the weapon will chamber as normal.

Question 8

No Go Gauge

Answer 8

This gauge should not fit the weapon’s headspace; therefore the weapon should not camber properly or lock.

If this gauge does fit the weapon’s headspace then the weapon is no longer serviceable because the headspace has expanded most likely due to extreme usage.

Question 9

Field Gauge

Answer 9

This is used to determine when a weapon is outside of its specs and no longer used.

Question 10

Muzzle Break

Answer 10

A device at the end of the weapon which deflects the gases as they exit the muzzle of the weapon; this in turn helps to reduce some of the rearward felt recoil.

Question 11

4 Types of Muzzle Devices

Answer 11

Flash Hider
Muzzle Brake
Compensator
Hybrid

Question 12

Flash Hider

Answer 12

Found on short barreled rifles.

Used because the propellant is still burning as the bullet leaves the barrel (which creates a fireball effect).

Question 13

Muzzle Brake

Answer 13

Deflects powder gases as they exit the weapon. Also helps reduce recoil.

Question 14

Compensator

Answer 14

Aid in reducing recoil, rise, and recoil felt by the shooter.

Question 15

Hybrid

Answer 15

Combines characteristics from any other two categories of Muzzle Devices.

Question 16

Fluted Chamber

Answer 16

Slots cut in the chamber of a weapon which allow for gases from the fired cartridge to enter the chamber. These gases create a buffer between the cartridge case and the chamber wall that aids in the extraction of the cartridge case from the chamber.
A fluted chamber will leave horizontal “burn” marks on the spent cartridge case produced by the gases that cycle the weapon.
The purpose of a Fluted Chamber is to ensure the extraction of the cartridge case.

Question 17

Rifling

Answer 17

Helix grooves in the bore of the weapon which spin the bullet for accuracy.

Question 18

Lands

Answer 18

The raised portion between the grooves in the bore of a gun that impart the spinning motion to a bullet.

Question 19

Grooves

Answer 19

The valley portion of the rifling in a barrel that in conjunction with the lands impart the spinning motion to a bullet.

Question 20

Twist Ratio

Answer 20

1 Turn: # of inches required
1:7= 1 turn for every seven inches traveled by the bullet.
Larger ratios are required to accurately shoot lighter rounds.
A round will be unstable in flight if you do not use the properly weighted rounds with the corresponding twist ratio.

Question 21

How Rifling Is Made

Answer 21

1. Cutting one groove at a time with a machine tool. (Cut Rifling or Single Point Cut Rifling)
2. Cutting all of the grooves in one pass with a special progressive breeching bit. (Broached Rifling)
3. Pressing all of the grooves at once with a tool called a “button” that is pushed or pulled down the barrel. (Button Rifling)
4. Forging the Barrel
5. Flow forming the Barrel

Question 22

Polygonal Rifling

Answer 22

*Lasts 5-10% longer than traditional rifling.
*Optimum caliber- .45 ACP
2 Types- Hexagonal, Octagonal

Question 23

Extractor

Answer 23

A component which attaches to the rear of the cartridge groove or rim which is used to pull the cartridge from the chamber.

Question 24

Ejector

Answer 24

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.

• Found 180 degrees/ opposite from the ejection port
• May also be a tang of metal attached to the Receiver, (common on pistols) this is normally indicated by the cut out on the bolt group
• AK has a groove on the bolt that acts as its ejector

Question 25

Disconnector

Answer 25

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/ the weapon is in full battery.

Question 26

Sear

Answer 26

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

Question 27

Battle Sight

Answer 27

The range at which you can hit a target between the throat and waist without making a sight adjustment.

Question 28

Choke

Answer 28

An inside bore constriction at the muzzle end of the shotgun’s barrel.
*When a shot shell is fired, the shot travels down the bore, exits the muzzle, and begins to spread out. Chokes also increase effective range of the weapon.

Question 29

Trigger Bar

Answer 29

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

Question 30

Trigger

Answer 30

A finger actuated level used to activate the firing mechanism firing the weapon.

Question 31

Chamber

Answer 31

The unrifled portion of the bore at the rear end of the barrel that receives and supports the cartridge when the breach is closed. The chamber aligns the bullet with the bore and the primer with the firing pin.

Question 32

Firing Pin

Answer 32

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

Question 33

Compensator

Answer 33

A component at the muzzle end of a weapon that has slots in the top to vent gases from a fired cartridge upward as they live the barrel. The bottom of the component is solid in order to use the gases from the fired cartridge to force the barrel of the weapon downward.