GAU-21 Flashcards
-1 PDF 1272
What does “in battery” mean?
Bolt is in forward position
-1 PDF 1272
What does it say regarding using checklists during weapons emergencies? NOTE
Due to the nature of weapon emergencies, the use of checklists is not always practical. Perform steps 1-4 immediately.
-1 Malfunctions
What are the immediate actions for malfunctions? GAU - 21
- Notify Crew “_____ gun bent”
- Gun trained on target
- Forward Fire Switch OFF
- Charge Gun
-1 PDF 1271
Safe vs Safe and Clear
Safe= weapon does not render a dangerous condition
Safe and Clear= weapon has been visually checked to be clear of ammunition and does not render a dangerous condition
-1 PDF 1271
Weapons System Malfunction General
The operators first concern will be…
Safing the weapon
-1 PDF 1272
Misfire Definition
Complete failure of the weapon to fire.
-1 PDF 1272
Hang fire Definition
A delay in the function of the propelling charge. A hang fire cannot be distinguished immediately from a misfire and therein lies the principal danger.
-1 PDF 1272
Cook-Off Definition
Firing of the explosive components of a round due to overheating of the weapon and not due to actuating the firing mechanism.
-1 PDF 1272
Runaway Gun Definition
Failure of the weapon to cease firing when the triggers are released.
-1 Major Components
PDF 906
Auxiliary return springs assembly
Back plate assembly
Barrel & barrel extension
Barrel buffer assembly
Barrel jacket assembly
Bolt assembly
Feed cover assembly
Receiver assembly
Trigger assembly
Section IV GAU-21 CAUTION
Window closed
Ensure weapon is locked forward to prevent damage to gunners window
SECTION IV GAU-21 CAUTION
Stepping
Stepping on the ammunition can cover or the medium external connection assembly may cause damage
SECTION IV GAU-21 CAUTION
Ammo can front fairing
Lifting the ammunition can cover by the front fairing may cause damage
SECTION IV GAU-21 CAUTION
Probe
When probe is extended, round trajectory can be less than 6 inches from probe
SECTION IV GAU-21 NOTE
Vox
Firing weapons may actuate the pilots or copilots intercoms system when using VOX
SECTION IV GAU-21 NOTE
100 knots
Significant force is required to move all weapons forward of the 3-9 line when traveling at airspeeds above 100 kts
SECTION IV GAU-21 NOTE
When weapons aren’t being used
They should be stowed forward down position during taxi, takeoff, and landing (unless threat condition prohibits stowing)
SECTION IV GAU-21 CAUTION
Ammo chute
Failure to connect the ammunition chute to the gun can result in the loss of ammunition overboard and/or damage to airframe and weapon system components
SECTION IV GAU-21 CAUTION
Barrel cooling, what is this caution protecting?
Allow the barrel to cool to ambient (approx 2 min 30 sec) after firing a sustained long burst of approximately 100 rounds or many short bursts in quick succession. cooling to ambient varies depending on the environment conditions.
It’s to preclude damage to the gun barrels
Burst Limitations Table (Only when Static aka Hover Fire)
11W-13-21-2 PDF 60
1.5 sec burst = 30 sec cooling
3 sec burst = 1 min cooling
6 sec burst = 2 min 30 sec cooling
WARNING What is mandatory after firing 600 rounds?
11W-13-21-2 PDF 60
Complete cooling of the barrel to avoid injury to personnel and ensure optimal performance of the weapon.
Major Assemblies (salute)
11W-13-21-2 PDF 62
Barrel Assembly
Receiver Assembly
Bolt Assembly
Barrel Buffer Assembly
Feed Cover Assembly
Back Plate Assembly
Auxiliary Return Springs Assembly
Trigger Assembly
What is the purpose of the barrel extension assembly?
11W-13-21-2 PDF 63
Forms the link between the barrel and the barrel buffer assembly.
What ensures correct connection with the barrel extension and barrel buffer assembly?
11W-13-21-2 PDF 63
The rear shank of the barrel extension.
Where is the breech lock?
11W-13-21-2 PDF 63
It’s inserted into the rear of the barrel extension subassembly.
What is significant about the breech lock movement?
11W-13-21-2 PDF 63
It is secured to have restricted vertical movement by means of the breech lock pin. This allows it to travel along the breech long cam upward.
What is the receiver assembly’s purpose?
11W-13-21-2 PDF 64
Support, protect, and house various assemblies.
What piece has the bent metal piece we check on preflight it ensure that it won’t block links?
11W-13-21-2 PDF 64
The link guide adapter assembly.
Where is the breech lock cam located?
11W-13-21-2 PDF 65
The bottom of the receiver assembly.
What guides the extractor assembly? Where is it located?
11W-13-21-2 PDF 65
Extractor Switch
It’s located on the inner left hand side plate of the receiver assembly.
What forces the breech lock down? (Unlocking it from the bolt?)
11W-13-21-2 PDF 65
The breech lock depressors
On preflight, what piece can you physically see at the attachment point of the barrel to the receiver?
11W-13-21-2 PDF 66
The Trunnion Adapter
What secures the barrel jacket and flash suppressor onto the receiver?
11W-13-21-2 PDF 66
The trunnion adapter, trunnion adapter shim, and trunnion lol
What holds back the bolt?
11W-13-21-2 PDF 69
nice
The bolt latch assembly
What is happening when the triggers are depressed?
11W-13-21-2 PDF 69
nice
The bolt latch is rasied by the bolt latch pawl, so it releases the bolt assembly
What is the configuration when the safing selector is in the FIRE position?
11W-13-21-2 PDF 69
nice
Firing cam is blocked by the timing adjusting screw.
Sear slide will come into contact with the timing adjusting screw, it’s forced to move right, thus pressing the sear down, thus releasing the firing pin extension assembly.
What ensures that the feed cover does not close inadvertently after it has been opened?
11W-13-21-2 PDF 69
nice
The cover detent pawl (it’s held into place with spring tension by it’s cover lock spring
What does the bolt assembly control/purpose?
11W-13-21-2 PDF 71
Feeding, extracting, ejectiong, firing pin operation (technically)
What is located on top of the bolt to form a continuous groove for the belt feed lever lug on top of the bolt assembly?
11W-13-21-2 PDF 71
The alternate feed bolt switch
What’s the purpose of the cocking lever?
11W-13-21-2 PDF 71
It’s used to push the extension and firing pin assembly into its cocked position.
What holds back the rear of the firing pin spring when the extension and firing pin assembly is in the cocked position?
11W-13-21-2 PDF 71
Firing pin extension spring stop assembly.
What does the sear do?
11W-13-21-2 PDF 71
Holds back the extension and firing pin assembly back at its cocked position.
What’s the difference in purpose between the firing pin extension spring stop assembly and the sear?
11W-13-21-2 PDF 71
FPESSA= specifically holds the firing pin spring (WITHIN the firing pin extension as a whole)
Sear= holds the entire extension assembly
What piece is the extractor vs ejector?
11W-13-21-2 PDF 70
Ejector is the hook shaped thing.
The extractor is the whole “body” with the extractor switch on the side. So the extractor is moreso that little U shaped lip pointing downward
What is the functon of the extractor specifically?
11W-13-21-2 PDF 71
Removes a round of ammunition from the linked belt and guides the round into the T slot of the bolt assembly.
Why do we care about the barrel buffer assembly?
11W-13-21-2 PDF 73
It absorbs the recoil energy of the barrel assembly.
What do the buffer accelerators do? (the fingers lol)
11W-13-21-2 PDF 73
Accelerate the bolt away from the barrel extension assembly.
What ensures correct locking with the barrel extension?
11W-13-21-2 PDF 73
The buffer block subassembly (like an S grip between it and the barrel extension) See diagram on PDF 72
Where do the links vs spent cartridge cases go?
11W-13-21-2 PDF 75
Links go to the opposite side of the feeding
Cartridge cases are ejected through the bottom of the receiver assembly
What are the four main pieces of the feed cover assembly?
11W-13-21-2 PDF 75
- Feed cover
- Cover latch shaft assembly
- Belt feed lever
- Feed slide and pawl assembly
What safety measure is implemented into the cover latch shaft assembly?
11W-13-21-2 PDF 75
It cannot be opened when the safety firing assembly is at the upper FIRE position.
GO THROUGH A POWER OFF PREFLIGHT (not -1 but parts and pieces)
- safe and clear and switches
- unlock it
- disconnect link chute
- check ammo can to be empty
- keep it locked to the rear
- check inside barrel for buildup
- safety wire
- barrel jacket
- trunnion adapter is secure
- link chute (disconnect)
- hockey stick on link chute adapter assembly (secure)
- feed cover
- belt feed lever lug is there
- smooth operation with belt feed lever corrosponding to the belt feed slide and pawl
- spring tension on the belt feed pawl arm
- cover latch shaft assembly spring tension
- link guide adapter assembly metal piece isn’t bent inward
- front face of bolt not damaged or buildup
- send bolt forward
- extractor ejector, spring tension no missing parts
- alternate bolt feed switch is setup for correct side
- check firing pin (set to fire, rack it, send it forward, pin protrudes, set to safe, rack it, send it forward
- switches cover guarded down
- ICS has detent
- swing to the rear, not gonna shoot the stab
- cartridge links guide alligator clips work, disconnect and inspect, reattach
Why do we care about the back plate assembly?
11W-13-21-2 PDF 77
It is used to stop the bolt assembly at the end of the rearward movement and absorb the remaining recoil energy.
What safety measure is implemented to the back plate assembly?
11W-13-21-2 PDF 77
The back plate latch lock makes it impossible to accidentally release teh back plate assembly by inadvertently moving the back plate latch
Why do we care about the axuiliary return springs assembly?
11W-13-21-2 PDF 77
It helps push the bolt assembly toward the battery position
Why does this matter? I’m glad you asked. Because there needs to be enough force to pull the ammunition belt into the gun.
How would a malfunction with the auxiliary return springs assembly, driving spring, or spring rod assembly? (probably, in theory)
The bolt wouldn’t have enough forward movement to force the belt feed slide and arm to pull the next round in. Maybe, idk, I’m making this up to try and understand.
What three components are helping send the bolt toward the battery position?
11W-13-21-2 PDF 77
- auxiliary return springs
- driving spring
- spring rod assembly
What does the trigger assembly control?
11W-13-21-2 PDF 81
The bolt latch operation (holding the bolt back or releasing the bolt)
What are the two main phases?
11W-13-21-2 PDF 83
Counter Recoil
Recoil
What are the 8 actions (cycle of ops) taking place in chronological order?
11W-13-21-2 PDF 83
- feeding
- chambering
- locking
- firing
- unlocking
- extracting
- ejecting
- cocking
What happens when the trigger assembly is released?
11W-13-21-2 PDF 84
Cycle of operations will cease after the recoil phase.
With the bolt striking the bolt latch pawl and re-setting under the limit of travel pawl. This allows the bolt latch to drop down and re-engage the top of the bolt (lock to the rear in the open position)
Feeding Definition
11W-13-21-2 PDF 84
When the next live cartridge in the ammunition belt is pulled over the belt holding pawls and onto the feed table.
Chambering Definition
11W-13-21-2 PDF 84
Extractor rides underneath the extractor switch, ensuring the cartridge is positioned in front of the recessed firing pin and inserted into the chamber of the barrel.
What forces down the extractor as it comes back to the feed table? Why do we care?
11W-13-21-2 PDF 84
The extractor cover spring. We care becuase it makes sure proper tension is applied on the extractor lip of the next cartridge.
What is headspace?
11W-13-21-2 PDF 84
Insertion depth of the chambered cartridge.
Locking Definition (and what piece is locking)
11W-13-21-2 PDF 85
Locking is for the breech
Occurs when the bolt locks to the barrel extension.
Firing Definition (like no shit sherlock)
11W-13-21-2 PDF 85
Firing pin makes contact with the primer on the live round in the chamber.
Unlocking Definition
11W-13-21-2 PDF 85
When the bolt is released from the barrel extension.
What forces the breech lock down and off the breech lock cam, allowing the bolt to be unlocked?
11W-13-21-2 PDF 85
The breech lock pin (contacts the breech lock depressors on the inside of the receiver, this forces it down).
Extracting Definition
11W-13-21-2 PDF 85
Removing a live cartridge from the ammunition belt while simultaneously removing a cartridge case from the chamber.
Ejecting Definition
11W-13-21-2 PDF 85
Forcing the cartridge case out of the weapon.
Cocking Definition
11W-13-21-2 PDF 85
When the cocking lever on the bolt contacts the bolt latch bracket on the receiver. This cycles the cocking lever forward forcing the firing pin extension to the rear and locking it to the sear.
NOTE What is the difference between a stoppage and a malfunction?
11W-13-21-2 PDF 86
Stoppage is - interruption in the cycle of operation caused by the faulty action of the weapon or ammunition
Malfunction is - a part bending, breaking, or being worn to the point of being non-operational
What casues the bolt assembly to move rearward? Don’t saying charging it, don’t do it
11W-13-21-2 PDF 87
The recoil force of the cartridge firing
What causes faster rearward movement of the buffer accelerator? During rearward movement obvi
11W-13-21-2 PDF 89
Barrel extension continues moving rearward, the contact point between the barrel extension assembly and the buffer accelerator moves down.
What prevents a double feed?
Gouge
The belt feed arm spring tension. When the belt feed arm is depressed upward from a round the belt feed pawl assembly is connected so it can’t engage another round to be pulled in.
What’s an easy way to remember the major assemblies?
Phonetics
FART 5 B’s
