Thanks to PoundofLife89-_- over on PSNProfiles for this inspiration for this guide- From the main menu, choose Co-op Campaign
- Choose Online (Private)
- Select Episode 3: Moscow, then A Sign from Above
- Choose Change Class then select Fixer
- IMPORTANT: Ensure your class is starting with a supply bag, as this will allow you to refill your ammo (for certain weapons at least). I'd suggest the Armory and Knock Knock skill perks.
- Inside Game Settings, choose Mutators
- Turn on the following mutators:
- Restless Horde (fifth 'unique' section),
- All Flash, No Bang (sixth 'unique' section), and
- Thief and Looter (both in the common section, about half way down the list of mutators)
You can now select
Ready to start playing through the level as usual. Make sure to keep an eye out for weapons around the level as you progress. You
won't see weapon crates using the above mutators, but you can press
to drop a supply bag and then restock your weapon from that.
At any time, you can press
button to check the XP progress of the weapon you have selected - if the XP bar in the bottom right isn't full, you need to fire it at zombies to increase it (special zombies will give you higher XP than ordinary zombies). Unfortunately, the XP required per level seems to vary depending on the weapon.
Once you have maxed out the XP for a particular weapon, find another weapon in the level that you need to progress and use that instead. You can also swap between weapons you have currently on you by pressing
.
The mutator options should allow you to find quite a lot of Tier 2 and Tier 3 weapons in the middle section of the level (when you're resetting alarms and fighting waves of zombies). Additionally, if the alarm is ringing and you
DON'T continue with using other alarm panels, you should be able to infinitely spawn zombies and gain weapon XP.