Go go gadget white stuff applier
 Hive Scum Build - Warhammer 40k: Darktide 

This is pretty much Veteran with actually infinite ammo which makes Branx MkIII Dual Autopistols your PRIMARY WEAPON.

It is stupid, it is fun and it is somehow highly effective.

The main idea is using your autoguns 99% of the time while cycling Cartel Special and Desperado.

DO NOT USE THIS BUILD WITH ROTTEN ARMOUR MODIFIER ON HAVOC

Pickpocket 

This talent is just stupid. It restores your ammo reserve back to 20% when you're bellow 20% when you kill Elite or Special enemy which you have brazillion on Auric and Havoc. 
Which simply means that you can't run out of ammo. Every time you kill Elites or Specialists you get almost 2 mags back for free. 

Enhanced Desperado 

Oh you're in for it now. This is your primary survival tool. Description doesn't mention it but it actually replenishes your toughness to full. Autopistols have very low rending on their own but with Pick Your Targets you get just barely enough penetration to deal low but sustained damage on Carapace enemies.

Vulture's Mark 

This keystone at 3 stacks gives you a total of:

• +15% Ranged damage 
• +15% Ranged critical chance
• +15% Movement speed

Also, while at max stacks, killing Specialists and Elite RANGED Enemies replenishes 15% Toughness to your teammates.

At 3 stacks you will have 40% Crit chance meaning Vulture's Dodge is active as long as you keep shooting at enemies which means effective invincibility and Patient Hunter makes sure you have those stacks for as long as possible.

Cartel special

When you stimm you get:

• 25% Cooldown regeneration
• 75% Cooldown regeneration on Ranged kills for 1s
• 20% Strength 
• 15% Rending

Considering this you should pop your stimm AFTER Enhanced Desperado to achieve quick Ability cooldown regen.

Once your Ability cools off use it to get your stimm back with Sample Collector. You can use Improvised Mk I Shivs throwing gimmick to get a little bit more cooldown off. 

Chem Grenade 

Very stupid Blitz and might just be the strongest one in the game as of right now. It pretty much disables area that you throw it at and gives you shit ton of your stimm back. You can even throw it at Heinous Ritual from distance to kill a bunch (or all) of Ritualists and slow down Daemonhost summon.

In summary: 

• Your gameplay is focused on being anti-elite, anti-horde and anti-specialists. 
• You can give space for your team using Chem Grenade or boosting damage against clusters of heavily armored enemies.
• You don't need any ammo pickups because of Pickpocket. With Psyker in your team only a maximum of 2 other players will be needing ammo pickups.
• You can't pick up regular stimms which means all of them go to your team.
• Your greatest weakness is Carapace armour so leave those Crushers to your team and deal with everything else.
• Havoc 40 ready