Updated October 24, 2026
Stuck at the Air Base Armory door in Call of Duty: Modern Warfare 4 DMZ? The bunker requires a changing six-digit code assembled from three Transfer Slip notes, plus a separate Armory Access Card.
Even if your keypad code is correct, the door can display “NO AIRBASE ARMORY ACCESS CARD IN INVENTORY” when you are carrying the ordinary Multi-Use card instead of the required armory card.
During Operation Iron Citadel, you must find all three code fragments inside Chang-san Air Base Bunker, upgrade the mission access card, and satisfy both security requirements.
This guide explains every note location, how to get the correct access card, and what to check if the code tracker or armory door is preventing you from progressing.
📋 Table of Contents
- Quick Answer: What Is the Armory Code?
- Does the Armory Code Change?
- How to Get the Armory Access Card
- Can't Find the Initial Access Card?
- Access Card Upgraded but Objective Won't Advance?
- Where Is the Air Base Armory Door?
- First Code Note: Administration Conference Room
- Second Code Note: Medical Wing Laboratory
- Third Code Note: Control Room
- How to Assemble and Enter the Code
- Known Digits Stuck at 2/3?
- Armory Door Not Opening?
- What Happens After Opening the Armory?
- Frequently Asked Questions
- Final Tips
Quick Answer: What Is the Air Base Armory Code in MW4 DMZ?
The Air Base Armory code is not the same in every deployment. You must find three Transfer Slip notes and combine their two-digit fragments in the correct order.
The notes are located in:
- Administration Conference Room: First Segment, on the central conference table.
- Medical Wing Laboratory: Second Segment, on a laboratory desk.
- Control Room: Third Segment, near the control workstations.
For example, if your notes display 71, 75, and 66, the complete six-digit code is 717566.
Important: This is an example, not a universal code. Use the digits from your own deployment.
You also need the Air Base Armory Access Card, obtained by upgrading the initial mission access card in the upstairs Server Room of Admin Complex No. 2.
The ordinary Air Base Access Card – Multi Use (B5) and the DRC Weapons Locker Key (B6) cannot replace the armory-specific card.
Does the Air Base Armory Code Change?
Yes. The armory uses a six-digit combination assembled from three separate two-digit fragments.
Each fragment appears on a document titled Transfer Slip — Do Not File. The notes identify themselves as armory access code fragments and specify whether they contain the first, second, or third segment.
The digits can change between deployments. For example, the first segment might be 71 in one deployment and 52 in another.
This means that a code copied from another player's mission may not unlock your armory.
The important rule is simple:
Arrange the fragments by their First, Second, and Third Segment labels—not by the order in which you find them.
You might discover the second fragment before the first, but the keypad still requires the complete combination in the correct sequence.
If your mission tracker displays Known Digits, use it to check your progress as you read the three notes.
How to Get the Air Base Armory Access Card
Before attempting to unlock the bunker armory, obtain the correct access card during Operation Iron Citadel.
The required card is an upgraded, single-use armory access item. It is different from the ordinary Multi-Use card used for other restricted doors around Chang-san Air Base.
Step 1: Find the Initial Access Card
Start Operation Iron Citadel and follow the objectives directing you to search buildings at Chang-san Air Base.
The mission uses access-card scan information to narrow down the correct building.
Check the indicated locations and collect the initial access card when you find it.
Do not assume that the card will always be in the same building shown in another player's walkthrough.
Step 2: Reach Admin Complex No. 2
After obtaining the initial card, travel to Admin Complex No. 2.
Enter the building and make your way upstairs to the Server Room.
The Server Room contains the equipment used to upgrade the card for armory access.
Clear nearby enemies before starting the interaction, since you must defend the area while the upgrade runs.
Step 3: Upgrade the Card
Interact with the Server Room card reader to begin the upgrade.
Defend the area until the process finishes.
Once the upgrade is complete, look for the interaction:
“TAKE ARMORY ACCESS CARD”
Collect the finished card and check for the “ACCESS CARD UPGRADED” confirmation.
Do not leave immediately after the upgrade finishes. Make sure the completed Armory Access Card has actually been collected.
You can then continue toward Chang-san Air Base Bunker to locate the three code fragments.
Can't Find the Initial Access Card?
The initial access-card search does not have one guaranteed building location.
During Operation Iron Citadel, follow the mission-designated search areas and pay attention to scan updates that help identify the correct building.
If you do not find the card in the first location, continue checking the remaining marked buildings.
Once the mission identifies the correct location, collect the card and proceed to Admin Complex No. 2.
Tip: Follow your current mission markers rather than relying on a fixed building location from another deployment.
Access Card Upgraded but Objective Won't Advance?
Finishing the Server Room upgrade does not necessarily mean the completed card has been collected.
If the objective remains active, return to the upgrade equipment and check for the “TAKE ARMORY ACCESS CARD” interaction.
Make sure you have:
- Found the initial mission access card.
- Started and completed the Server Room upgrade.
- Collected the finished Armory Access Card.
- Confirmed the mission has registered the upgrade.
If the upgrade is complete but the mission still has not progressed, check the Server Room for an unfinished interaction before leaving the building.
Where Is the Air Base Armory Door?
The armory is located inside Chang-san Air Base Bunker, an Extreme-threat area.
After entering the bunker through the Entrance Garage, continue into the interior corridors and look for the restricted armory entrance.
The door is recognizable by:
- A heavy, reinforced vault-style metal door.
- A numerical keypad beside the entrance.
- Korean warning signs indicating a restricted officers-only area.
- An “ENTER ACCESS CODE” interaction.
The armory uses two separate security requirements: the keypad combination and the Armory Access Card.
Finding the door does not mean you can open it immediately. You must first satisfy both requirements.
Watch Out for Commander Colossus
The bunker can become especially dangerous when Commander Colossus, a heavily armored enemy equipped with a minigun, enters the fight.
Avoid standing in exposed corridors while reading notes or interacting with the keypad.
Use nearby cover, maintain your armor, and reposition when necessary.
If you are playing with a squad, one player can watch the corridor while the others search for the code fragments.
You should also keep enough backpack space for important mission items. If inventory management becomes a problem, see our MW4 DMZ Backpack Full guide.
First Code Note: Administration Conference Room
The first armory code fragment is found in the bunker administration section.
Look for a large conference room containing a long central table.
The table has a tactical map, documents, and other office materials scattered across its surface.
How to Find the First Note
- Enter the administration area of Chang-san Air Base Bunker.
- Locate the conference room with the large central table.
- Approach the documents on the tabletop.
- Look for the “READ NOTE” interaction.
- Open the Transfer Slip and identify the First Segment.
The document is titled Transfer Slip — Do Not File.
It explains that the armory access code has been divided into separate fragments as part of the base's security procedures.
One possible note displays:
First Segment: 71
Your own note may show different digits.
Record the number before leaving the conference room.
Image caption: The first armory code fragment is on the central conference table in the bunker administration area.
Second Code Note: Medical Wing Laboratory
The second armory code fragment is located in the bunker medical wing.
Instead of a conference table, look for a laboratory desk surrounded by medical equipment and test-tube racks.
How to Find the Second Note
- Enter the bunker medical section.
- Locate the laboratory area containing test-tube racks and work surfaces.
- Search the desk with documents spread across it.
- Approach the readable document until “READ NOTE” appears.
- Open the Transfer Slip and record its Second Segment.
One possible note displays:
Second Segment: 75
This fragment is held separately from the administration note.
Do not confuse the readable document with nearby medical supplies. The area can contain First Aid Kits, Medical Bags, and other consumables, but the code fragment is a note that you must read.
Image caption: The second armory code fragment is found on a laboratory desk in the medical wing.
Third Code Note: Control Room
The third armory code fragment is found in the bunker Control Room.
This area contains industrial equipment, computer workstations, and control consoles.
How to Find the Third Note
- Continue through the bunker until you reach the Control Room.
- Inspect the readable documents near the control workstations.
- Find the Transfer Slip identifying itself as an armory access code fragment.
- Read the Third Segment.
- Check whether you now have all three fragments.
One possible note displays:
Third Segment: 66
The document explains that the keypad requires the complete six-digit sequence.
After reading the third note, check the mission tracker for confirmation that all required digits have been discovered.
Image caption: The third armory code fragment is located in the Control Room near the workstations.
How to Assemble and Enter the Six-Digit Code
Once you have found all three Transfer Slips, arrange their numbers in the labeled order.
The sequence must be:
First Segment + Second Segment + Third Segment
For example:
- First Segment: 71
- Second Segment: 75
- Third Segment: 66
Complete code: 717566
This is an example only. Use the digits displayed in your current deployment.
How to Enter the Code
- Return to the reinforced armory entrance.
- Approach the keypad beside the door.
- Use the “ENTER ACCESS CODE” interaction.
- Enter the six digits assembled from your three notes.
- Complete the separate Armory Access Card requirement.
If the keypad accepts your combination but the armory still refuses access, check your inventory for the upgraded armory-specific card.
The ordinary B5 Multi-Use card will not satisfy this requirement.
Known Digits Stuck at 2/3?
If your objective tracker displays Known Digits: 2/3, you are still missing one of the three code fragments.
Revisit the three note locations:
- Administration Conference Room: The large table with tactical maps and documents.
- Medical Wing Laboratory: The desk near medical equipment and test-tube racks.
- Control Room: The readable document near the control workstations.
Check which Transfer Slips you have already read and return to the area containing the missing segment.
Remember that the order in which you discover the notes does not matter. What matters is collecting the first, second, and third segments.
When the tracker reaches 3/3, check the objective information for the complete six-digit combination.
Use that code rather than copying a combination from another deployment.
Air Base Armory Door Not Opening?
If you have found all three fragments but the armory remains locked, read the exact error message.
A missing access card and an incorrect keypad combination are separate problems.
No Airbase Armory Access Card in Inventory
You may have an Air Base Access Card in your backpack and still receive this message:
“NO AIRBASE ARMORY ACCESS CARD IN INVENTORY”
The armory requires its dedicated upgraded card.
The ordinary Air Base Access Card – Multi Use is a different item and does not satisfy the armory reader.
Return to the Operation Iron Citadel access-card objective and confirm that you completed the Server Room upgrade and collected the finished card.
Air Base Access Card – Multi Use vs. Armory Card
Several similarly named access items can cause confusion.
Air Base Access Card – Multi Use (B5)
- Epic keycard.
- Used for restricted doors around Chang-san Air Base.
- Does not replace the armory-specific card.
Air Base Armory Access Card
- Obtained through the Operation Iron Citadel upgrade process.
- Identified as a single-use armory access item.
- Required for the main armory entrance.
Air Base DRC Weapons Locker Key (B6)
- A separate key for the DRC Weapons Locker.
- Used for a locker inside the secure armory.
- Does not replace the main armory access card.
If the terminal displays “REQUIRES AIR BASE ARMORY ACCESS CARD”, check that you are carrying the upgraded card rather than the B5 Multi-Use card or B6 locker key.
Correct Code but the Door Still Refuses Access
Check the following before restarting the mission:
- Use the current code. Do not rely on a combination from another deployment.
- Check the fragment order. Enter First, Second, and Third Segment.
- Verify Known Digits. Make sure the tracker has reached 3/3.
- Inspect your access card. Confirm that it is the upgraded armory-specific item.
- Check the Server Room upgrade. Make sure you collected the finished card.
- Read the exact door message. A missing-card error requires a different solution from an incorrect code.
If the door still refuses access after both requirements are satisfied, there is no confirmed universal workaround. Check the active mission objective and inventory state before discarding keys or restarting.
What Happens After Opening the Armory?
Opening the armory is one stage of Operation Iron Citadel.
Once inside, continue following the active objectives, including recovering the Armory Manifest and completing the required demolition and strike objectives.
The mission also involves a SAM-site objective and extraction.
Keep the Armory Manifest and other required mission items secure rather than replacing them with ordinary loot.
If you encounter problems with the SAM objective, our MW4 DMZ Capture SAM Site guide explains how capture progress works and what to check when the objective appears stuck.
For another keypad-related DMZ mission, see our Modern Warfare 4 DMZ Broken Resupply walkthrough, which covers its separate code and bomb-location objectives.
Frequently Asked Questions
What is the six-digit Air Base Armory code in MW4 DMZ?
The code changes between deployments. Find the three Transfer Slip notes and combine their labeled two-digit fragments. The example 717566 will not necessarily work in your game.
Where is the first armory code note?
On the large central conference table in the bunker administration section, among tactical maps and documents.
Where is the second armory code note?
On a laboratory desk in the bunker medical wing, near test-tube racks and medical equipment.
Where is the third armory code note?
In the bunker Control Room, near the control workstations and readable documents.
Why does 717566 not work?
717566 is an example combination. The digits can change between deployments, so use the numbers shown on your own three Transfer Slips.
Where do I get the Air Base Armory Access Card?
During Operation Iron Citadel, collect the initial mission access card, take it to the upstairs Server Room in Admin Complex No. 2, complete the upgrade, and collect the finished Armory Access Card.
Why can't I find the initial access card?
The mission can direct you to different search buildings. Follow the current scan updates and mission markers rather than assuming the card always appears in one fixed location.
Why is Known Digits stuck at 2/3?
You are missing one of the three Transfer Slip fragments. Recheck the administration conference room, medical-wing laboratory, and Control Room.
Why does the armory say I have no access card?
The armory requires the upgraded Armory Access Card. The ordinary Air Base Access Card – Multi Use is a different item and does not satisfy the main armory reader.
Can I use the B5 Multi-Use card to open the armory?
No. The B5 Multi-Use card is intended for other restricted doors around Chang-san Air Base.
Does the DRC Weapons Locker Key open the armory door?
No. The B6 DRC Weapons Locker key is intended for a separate locker inside the secure armory.
What if the access-card upgrade finishes but the mission doesn't advance?
Return to the Server Room and check whether the finished card is waiting to be collected. Look for the “TAKE ARMORY ACCESS CARD” interaction.
What should I do after unlocking the armory?
Continue Operation Iron Citadel by recovering the Armory Manifest and completing the remaining mission objectives, including the required demolition, SAM-site, and extraction stages.
Final Tips
The Chang-san Air Base Armory puzzle has two requirements that are easy to confuse.
First, find the three Transfer Slips and assemble the changing six-digit code. Second, obtain the upgraded Air Base Armory Access Card rather than relying on the ordinary Multi-Use card.
The administration conference room, medical-wing laboratory, and Control Room contain the three code fragments.
Once you have all three segments and the correct access card, return to the reinforced armory entrance and complete the unlock sequence.
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