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3 Steps to Unlock the M13B In Warzone

Unlock M13B Warzone
In this guide

The M13B is a secret Modern Warfare 2 assault rifle that can be unlocked by completing a particular challenge in DMZ mode. Once unlocked, players can use the M13B in Modern Warfare 2 Multiplayer, Warzone, or DMZ mode. This guide will detail three steps to unlock the M13B for Warzone.

Quick take

The M13B is a secret Modern Warfare 2 assault rifle that can only be unlocked in DMZ mode. To unlock the M13B in DMZ mode, players must find the special radiation zone, kill the Chemist, and exfil with the M13B. Exfilling with any M13B will do the trick, so friends can drop the weapon for each other once they’ve unlocked it.

How to unlock the M13B for Warzone

The M13B assault rifle can only be unlocked by playing Modern Warfare 2’s DMZ mode. Warzone players who want to unlock the M13B must find the special radiation zone in the DMZ, kill the Chemist, and successfully extract with his M13B.

Once you extract with the M13B, you’ll have access to a highly-accurate assault rifle that’s among the best loadouts for Warzone.

Below are the steps to complete the Chemist challenge and unlock the M13B for Warzone:

1. Find the special radiation zone

Call of Duty Modern Warfare 2 special radiation zone
Special radiation area marked on Tac-Map. Credit: Activision

The Chemist and his M13B assault rifle reside in a special radiation zone in DMZ mode. To find the special radiation zone, load into a DMZ match and look for a yellow circle with a pink biohazard symbol in the middle.

We recommend finding a car or vehicle to travel to and escape the radiation zone quickly. Only one player can extract with the Chemist’s M13B, so being the first to find him is essential.

Before you travel to the radiation zone and fight the Chemist, we recommend stocking up on some essential items. The radiation zone damages players over time; pick up a gas mask or radiation blocker item to prevent radiation damage. It’s also a good idea to bring a three-plate armor vest, armor plates, a medium backpack, ammo, grenades, and other items to help take down the Chemist and his guards.

Once you drive to the edge of the special radiation zone, leave your car outside of the radiation. Vehicles won’t operate in the zone, and you will need to car again after you kill the Chemist to make a quick escape.

2. Kill the Chemist

The Chemist is a formidable foe with armor and a posse of armed guards that will defend him to the death. Finding a group of players to help you take down the Chemist can significantly improve your chances of success.

Enter the radiation zone with your gas mask and begin to take out some of the regular AI enemies within the zone. Eliminating the initial AI enemies will thin the hoard for when the Chemist appears. Most AI enemies in the zone will drop a gas mask when killed, so just pick one up off the ground if your mask starts to run low.

After a short time in the radiation zone, the Chemist will be alerted to your presence and attack with his armed guards. The Chemist will be easy to spot; he’s covered head to toe in a bright yellow hazmat suit.

Find cover in a building or structure where you can shoot at the Chemist. You won’t want to be caught in the open when fighting him. Claymores and other explosives can be placed ahead of time to make light work of the Chemist when he arrives.

Once you kill the Chemist and his armed guards, he will drop an M13B blueprint called Health Hazard. Loot the M13B by equipping it or storing it in a medium/large backpack. Only one player in the lobby can loot and extract with the Health Hazard blueprint.

3. Exfil with the M13B

After killing the Chemist and looting the M13B, you will want to exfil as quickly as possible so that other DMZ players won’t steal your precious cargo. Get in the getaway vehicle and head straight to the nearest exfil point marked on the map with a blue exit symbol.

While extracting with the M13B quickly is crucial, don’t rush the exfil process. DMZ players love to camp the extraction points and ambush players trying to extract with the M13B.

Pro tip

Don’t hang around the green smoke once you call in the helicopter. Take cover in a nearby building or stay on the move in a vehicle to defend yourself from ambushes.

Scout out the area and call in the exfil helicopter once you determine the coast is clear. Successfully extracting with the M13B will put the Health Hazard blueprint in your contraband inventory for future use. The M13B will be unlocked for every Modern Warfare 2 game mode, including Warzone.

Other ways to unlock the M13B assault rifle

Call of Duty Modern Warfare 2 M13B dropped
Dropped M13B assault rifle. Credit: Jory Hollander and Activision

Defeating the Chemist and successfully extracting with his M13B can be an arduous process that usually requires the coordination of an entire team. Luckily, there is an alternative method to unlock the M13B for Warzone.

Exfil with any M13B in DMZ mode.

You don’t need to exfil with the Chemist’s Health Hazard M13B to unlock the gun for Modern Warfare 2. Exfilling with any M13B will do the trick.

Anyone who’s already unlocked the M13B can drop the weapon in DMZ mode for a teammate. Exfilling with a teammate’s M13B will unlock the weapon permanently across all Modern Warfare 2 game modes. Exfiling is a much safer way of unlocking the M13B, as long as you know someone who already owns it.

Looting the M13B from a slain DMZ enemy and exfilling will also unlock the weapon. This method requires more luck because you must be fortunate enough that the enemy you kill carries the M13B.

Once you have the M13B unlocked, you’ll want to acquire all of the weapon’s best attachments for Warzone. Check out our guide on how to level up guns fast in Warzone.


  • Can you unlock the M13B without DMZ?

    The M13B can only be unlocked by exfilling with the weapon in DMZ mode.

  • What is the easiest way to unlock the M13B?

    The easiest way to unlock the M13B is to have a teammate drop it for you in DMZ mode. Exfilling with a teammate’s M13B will permanently unlock the weapon for all game modes.

  • Why is the M13B not unlocking after extraction?

    The M13B will only be unlocked for the player who exfills with the weapon in their inventory. The M13B unlock will not be shared between a group or squad.

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Jory Hollander

I'm a Southern California native with over 25 years of experience gaming on PC and console. I love writing about gaming peripherals, esports, and a variety of FPS games. AMD Ryzen 7 7800X3D | MSI Ventus 3X OC GeForce RTX 4080 Super | Teamgroup T-Force Delta RGB 32 GB DDR5-6000 CL30 | Gigabyte B650 Aorus Elite | WD Black SN850X 1TB | Thermaltake Toughpower GF A3 850 W 80+ Gold | ID-Cooling Frostflow 240X | Montech AIR 903 MAX

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