Hobo with a Shotgun
 Hive Scum Build - Warhammer 40k: Darktide 

First ever build I wanted to share cause I was having a lot of fun with it. Any feedback is appreciated!
Tested on Auric Malestrom

Build centered around buffing the double barrel to be an absolute monster horde clearer and elite smasher. Spam the double shot into hordes and elites and watch them turn into a chunky, meaty, mist. 

Core Perks:
     - In your face
          Synergizes extremely well with double barrel. Useful to secure some kills at slight distance and hit one-shot breakpoints up close
     - Speed Loader
          As long as you kill with every blast, this perk is basically a permanent +30% reload speed which is very good on the double barrel.
     - Calling for a Time Out
          Double Barrel needs constant reloading. This perk incentives constant reloading. Obvious no-brainer to help with survivability.
     - Pick Your Targets
          Rending is absolutely needed to help get kills on some elites. The damage bonus is very nice too.
     - Pickpocket
          Infinite ammo as long as you kill specials and elites, which is what this build aims to do. Works with melee too so you'll never have to worry about stealing ammo from teammates.
     - Unload
         Another perk that incentivizes constant reloading, but this is the one I'm the most unsure about. The perk seems like it doesn't reset if you reload before it expires, but I don't have the technical know-how to dig into the code to find out. If it turns out it works the way I think it does, where it doesn't reset until it expires, then this is basically a permanent +22% damage buff, as you'll be losing 100% of your magazine with every double-shot. If it does reset with every reload, then take it out and replace it with Punching Above One's Weight
     - Hyper Critical
          Your shotgun should be constantly critting with this build, so this can help. However I am very unsure of how it works with shotgun pellets all hitting the same/multiple targets, it's still a very solid perk for melee.
     - Sample Collector
          The stimm setup will help you hit one-shot breakpoints vs a lot of chunkier elites, so getting it back as fast as possible is paramount to your elite smashing. 
     - Chemical Dependency, Chem Enhanced, Chem Fortified, and Maxxed Out Chems
          Cooldown for Desperado and Pick Your Targets, Crit chance for Man-Stopper, Chem Fortified for survivability, and Maxxed Out Chems for a nice bump to all of them. You can swap out MOC with Long Lasting if you wish for more time on stimm rampages
          NOTE: If you decide to take Long Lasting for the extra stimm duration, DON'T take Maxxed Out Chems. The total cooldown for the stimm will be 65 seconds, which is longer than the duration of Chem-Dependancy with MOC. So it will be very tricky to stack up chemical dependency, even with Sample Collector.
     - Stimm: Wildfire to Fury II
          The rending + strength here combined with Pick Your Targets is what turns the Double Barrel from a pure horde clearer to an apocalypse in two barrels. If you want more survivability take Barrage 1, but most of your survivability should be coming from the perk tree and not your stimm.
     Everything else can be taken as-needed depending on preference.
          
A question you might be thinking about right now is, "Why not Vulture's Mark?"
The simple answer is the benefits from Chemical Dependency are much better for what this build needs. The bonuses from vultures mark are better for builds that almost exclusively used ranged, and can constantly re-proc the perk. For this build, you're going to be relying on your melee more than you would in a typical desperado build that uses Auto Pistols or Dual Handguns. The extra cooldown from Chemical Dependency also allows you to use desperado more frequently, which is where we are getting half of our ranged armor-busting. The crit chance also applies to your melee, and not just ranged, which is very useful. 

Weapons
     - Ranged: Double Barrel Shotgun
          Perks: Man-Stopper and Scattershot
          Bonuses can be swapped as needed but recommend Reload + Maniac/Flak or Maniac + Flak
          The centerpiece of this build. Spam the double shot as much as possible into hordes and any specials or elites that get in your face. Use the single shot only on distant targets. Scattershot is important to constantly proc Man-Stopper and Hyper Critical, as well as one shot certain elites. Bonuses can be swapped as needed but I ended up choosing Maniac to help guarantee I could kill certain specials in a single shot. 
     - Melee: Crowbar (or any melee that can confidently kill Crushers)
          Perks: Can Opener + Opportunist 
          Bonuses: Up to preference but recommend at least Carapace/Elite
          One of the problems with this build is that, even with all the rending, crit, and bonus damage, the double barrel can't confidently take down Crushers. With every buff possible, you can kill one in about 3 double shots. But that's using both your stimm and desperado, which you won't have all the time. Your melee should be a good backup for these situations. I recommend the crowbar because it can  consistently stagger Crushers, even when they're in the middle of an attack. 

Problems with this build
          As mentioned above, Crushers can still be a problem even with all the buffs to damage and rending, and Bulwarks can be a bit troublesome too. As well, anything that can outrange you is a big problem. Gunners and Reapers can be dangerous in this regard, especially groups of them. Snipers even more so. And as with pretty much any Hive Scum build right now, boss damage isn't the greatest. You can mitigate these problems depending on your choice of Blitz. I chose Boom Bringer mainly for the boss damage and because my path to chemical dependency takes extra pouches. Boom bringer can clear squads of gunners from a distance and kill Bulwarks and Reapers on direct hits. Blackout is also a very solid choice, as the stun can allow you to close the distance, and because of the regen coming from kills, you'll constantly have some. But it won't help you versus bosses. Chem nade also helps kill groups of gunners, but I don't like to use it because I end up using it for horde clear when that's what the shotgun is supposed to be for. But for snipers, you're going to have to rely on teammates or pray you get a crit. Otherwise it may take up to 3-4 single shots depending on distance.