GAU-21, .50 Caliber Machine Gun

Question 1

Characteristics of the GAU-21, .50 caliber Machine Gun

Answer 1

Short recoil operated
Air-cooled
Fully automatic
Belt=fed
Fire from the open-bolt position
Fire .50 caliber ammunition

Question 2

The GAU-21, .50 caliber Machine Gun is a __________ weapon used as the fire suppression deterrent to ground troops, soft targets, light armor and fortified targets

Answer 2

defensive

Question 3

The GAU-21 rate of fire is:

Answer 3

950 to 1100 rounds per minute

Question 4

The max range of the GAU-21 is:

Answer 4

7000 meters

Question 5

The max effective range of the GAU-21 is:

Answer 5

3000 meters

Question 6

The tracer burnout of the GAU-21 is:

Answer 6

1500 meters

Question 7

Due to limited air flow at the ramp area, the GAU-21 requires time between firing bursts to __________ ______and to assist in avoiding the possibility of a cook-off. These limitations are based on the type of ammunition used.

Answer 7

properly cool

Question 8

GAU-21 component composed of the barrel and barrel extension assembly

Answer 8

barrel assembly

Question 9

GAU-21 component that consists of the trigger, back plate, back plate latch and back plate latch lock

Answer 9

Back plate assembly

Question 10

GAU-21 component that assists the rod assembly when pushing the bolt assembly to the battery position, ensure there is enough force to pull ammunition belt correctly into the weapon. Addition to supplying supplementary force for feeding also ensures correctly balance force is applied to the bolt assembly resulting in smooth operation of the weapon.

Answer 10

Auxiliary Return Spring Assembly

Question 11

GAU-21 component the provides feeding, stripping, cocking, chambering, firing, extraction, and ejection of cartridges during recoil and counter recoil.

Answer 11

Breech Bolt Assembly

Question 12

GAU-21 component that absorbs the recoil energy of the barrel assembly

Answer 12

Barrel Buffer Assembly

Question 13

GAU-21 component that provides the feed mechanism

Answer 13

Feed Cover Assembly

Question 14

GAU-21 component that supports, protects and houses various assemblies and is broken into 3 parts

Answer 14

Receiver Assembly

Question 15

GAU-21 component that is used to protect the barrel and minimize muzzle flash

Answer 15

Barrel Jacket Assembly

Question 16

GAU-21 component that controls the operation of the weapon, and begins the cycle of operation

Answer 16

Trigger Assembly

Question 17

The _______ ramp mount system is a non-electrical crew-served weapon system fired from the aft end of the aircraft ramp at the centerline

Answer 17

CV-22

Question 18

What consists of one mounted GAU-21 .50 caliber machine gun and or the M240 7.62 NATO machine gun mounted on the ramp of the CV-22

Answer 18

RMWS (Ramp Mounted Weapons System)

Question 19

The RWMS can be employed in the ___________, _________ and __________ modes. It can also be employed on the ground with the ramp level.

Answer 19

Hover (HVR)
Conversion (CONV)
Airplane (APLN)

Question 20

All actions in the cycle of operation for the GAU-21 takes place during one of these two phases

Answer 20

Counter Recoil Phase

Recoil Phase

Question 21

The beginning of the cycle of operations for the GAU-21. It is initiated by depressing the trigger assembly, which lifts the bolt latch and allows the compressed rod assembly spring to expand and send the bolt assembly forward to the battery position.

Answer 21

Counter Recoiling

Question 22

The compressed barrel buffer assembly helical spring also expands and send the barrel and barrel extension forward to the battery position. As these assemblies move forward these four actions occur sequentially:

Answer 22

feeding a round into the feed table
chambering a round
locking the breech
and firing a round

Question 23

_____________ of the cartridge to be fired is accomplished by the forward movement of the bolt. As the bolt moves forward, the extractor rides underneath the extractor switch, ensuring the cartridge is positioned in the front of the recessed firing pin and inserted in the chamber of the barrel.

Answer 23

Chambering

Question 24

__________ of the breech occurs when the bolt locks to the barrel extension. During the counter-recoil phase, the bolt moves forward independently of the barrel and barrel extension. As the bolt moves forward it comes into contact with and releases the accelerators.

Answer 24

Locking

Question 25

When the ___________ are released, the compressed springs in the barrel buffer assembly expand and send the barrel and barrel extension forward. As the barrel and barrel extension move forward, the breech lock rides up and the breech lock cam and lock into the bottom of the bolt.

Answer 25

accelerators

Question 26

At the point the bolt is locked to the barrel extension, and both assemblies move as one to the __________ position

Answer 26

battery

Question 27

__________ occurs when the firing pin makes contact with the primer on the live round in the chamber. As the bolt moves forward the sear slide contacts the firing cam on the FIRE-SAFE safety assembly. The firing cam pushes the sear slide inboard, which depress the sear. The sear is depressed; the firing pin extension is released allowing the compressed firing spring to expand, sending the firing pin forward, striking the primer on the chamber cartridge. The counter-recoil phase end with the bullet being fired, which also begins the recoil phase.

Answer 27

Firing

Question 28

The ____________ _________ is initiated by the rapidly expanding gases generated as a bullet is being fired. These rapidly expanding gases drive the barrel extension assembly and bolt to the rear of the weapon

Answer 28

recoil phase

Question 29

During the recoil phase, these 4 actions take place simultaneously:

Answer 29

unlocking the breech, extracting the next live cartridge from the ammunition belt and spent cartridge case from the chamber, ejecting the cartridge case and cocking

Question 30

__________ _____ ___________ happens when the bolt assembly is released from the barrel extension. In the beginning of the recoil, the barrel extension assembly and the bolt assembly travel together as one. The breech lock depressors on the inside of the receiver, forcing the breech lock down and off of the breech lock cam and unlocking the bolt.

Answer 30

Unlocking the breech

Question 31

Unlocking the bolt, allows the bolt to move independently of the barrel extension during the rest of the __________ __________. During the rearward movement of the bolt, the upper tips of the buffer accelerator contact the rear lower projection of the bolt. The energy of the rotating buffer accelerator will be transferred to the bolt.

Answer 31

recoil phase

Question 32

The bolt then continues its accelerated movement to the rear. The buffer plate and regulator tube absorb the ________ _________from the bolt while the barrel buffer assembly absorb the recoil and provide counter-recoil energy for the barrel-extension assembly.

Answer 32

recoil energy

Question 33

After the accelerator has been released from the bottom of the bolt, the accelerator continues rotating until its claws lock the rear shank of the barrel extension to the buffer block assembly. This causes the barrel extension assembly to be locked to the ________ ________ ________ .

Answer 33

barrel buffer group

Question 34

__________ is a two part process of removing a live cartridge from the ammunition belt while simultaneously removing a cartridge case from the chamber. As the bolt moves to the rear during recoil, the execrator subassembly contacts the groove on the rear of the cartridge that is against the cartridge stops, and it pulls the live cartridge from the ammunition belt. Simultaneously, the cartridge is removed from the chamber via the T-slot of the bolt.

Answer 34

Extracting

Question 35

__________ occurs after the extraction and is the process of forcing the cartridge case out of the weapon. As the bolt moves to the rear, the extractor is forced down by the cover extractor guide on the feed cover, which causes the extractor to push the spring loaded extractor switch down.

Answer 35

Ejection

Question 36

The _________ rides off of the aft end of the extractor switch, positions the live cartridge into the T-slot on the front face of the blot and forces the cartridge case out of the underside of the receiver. When the final bullet is fired, the ejector forces the cartridge case out of the receiver.

Answer 36

extractor

Question 37

__________ happens when the coking level on the bolt contacts the bolt latch bracket on the upper receiver. This cycles the cocking level forward, forcing the firing pin extension to the rear and locking it to the sear. The rear movement of the firing pin extension causes the firing pin extension against the firing pin spring stop assembly

Answer 37

Cocking

Question 38

The _________ phase ends when the bolt contacts the buffer plate on the back plate assembly

Answer 38

recoil

Question 39

____________ ___________ will continue as long as the trigger is depressed and the weapon is on fire, The cycle of operation will continue until the trigger assembly is released.

Answer 39

Automatic firing

Question 40

When the ________ is released, the cycle of operation will cease after the recoil phase, with the bolt striking the bolt latch pawl of the limit of travel pawl, allowing the bolt latch to from down and re-engage the top of the bolt. This will cause the bolt to lock to the rear in the open-bolt position

Answer 40

trigger

Question 41

The purpose of the GAU-21 and accessories inspection is:

Answer 41

to ensure that the accessories meet mission requirements and are in operational condition

Question 42

As a Special Missions Aviator, it is important to know the ___________ and ________ ___ ___________ for the .50 caliber machine guns. This will enable you to properly utilize the weapon on the battlefield

Answer 42

nomenclature | cycle of operation