New Modern Warfare 2 gun can only be unlocked by playing Warzone 2

Warzone 2 launched today alongside Modern Warfare 2's Season 1 update, joining the latest premium Call of Duty game at the hip with its free-to-play battle royale sibling. The two games share a lot: weapons pools, progression systems, and battle pass progress are all synced between both games. Traditionally, it's possible to unlock everything by playing either normal multiplayer or Warzone, but one of Season 1's new guns is locked behind a Warzone-exclusive challenge.

The M13B, an assault rifle Infinity Ward is touting for its high fire rate and low recoil (two stats you love to see on a CoD gun), is the only new gun in today's update that you can't simply unlock by progressing the battle pass.

The requirements to unlock the M13B instead involve jumping into Warzone 2's new sandboxy extraction mode, Warzone 2 DMZ.

Unlocking the M13B assault rifle in Warzone 2

The challenge description for the M13B assault rifle reads as followed:

"Unlock by defeating the Chemist in the radiation zone of DMZ and extracting his dropped weapon."

For what I believe is the first time in Call of Duty history, a gun is locked behind a PvE boss battle. You'll find the Chemist in the special radiation zone in Al Mazrah, but only if you're playing DMZ, not battle royale. The zone is marked by yellow on the tac map, here's what it looks like:

A few things to keep in mind to complete this challenge:

• Only the first team to arrive and defeat the Chemist can pick up his M13B rifle
• The radiation zone damages players over time, unless you have a gas mask
• You'll probably want a full squad of three to fight the Chemist
• Only the player who is holding the M13B upon exfiltration unlocks the weapon

The chemist's exact location isn't marked on the map, but he can be identified by a yellow hazmat suit. He's heavily armored himself and has a pile of armored goons backing him up, so come prepared. Once killed, his M13B can be picked up. The Chemist carries a special M13B blueprint pre-fitted with attachments and a cool yellow camo.

If you want to see the Chemist fight for yourself, YouTuber Geeky Pastimes' brief video guide is a great help:

Extracting with the gun won't unlock the blueprint permanently (though it'll persist in your DMZ inventory as contraband), but it will unlock the M13B for use in battle royale and multiplayer. The only major bummer here is that you'll have to make repeat trips to DMZ to unlock the M13B for your whole squad—only the player holding the gun upon extraction actually gets the unlock.

The good news is you may not have to kill the Chemist three times. Since all you have to do is be holding the gun at the end of the match, it's possible for a friend to drop the Chemist's M13B earned in a previous match, pick it up yourself, extract, and get the unlock. Alternatively, you could hunt down a rival player who's already killed the Chemist and take the M13B from them.

As for Modern Warfare 2 players who'd rather stick to regular 6v6 multiplayer, there's currently no path to unlocking the M13B. That may change in the future, but this seems to be a deliberate choice by Activision to promote Warzone 2's launch. The other two guns added today, the BAS-P SMG and Victus XMR sniper rifle, are unlockable via the Warzone 2 Battle Pass.