Hive Scum Melee Chad
 Hive Scum Build - Warhammer 40k: Darktide 

Notable Variations: 

1) Most important choice: Stimm Lab tree
You either do what's pictured above (47s cooldown focused sitmm) and you use it after the ult is over (when you can dive into melee) to pull the ult off cooldown very fast. This setup has very high ult uptime, but the stimm does nothing else it just maximizes the amount of time you are in your ult. 

The second option is to extend into the upper right branch up to either Fury II, or Wildfire V. Both are good, depends on team, but rending is more often useful in havoc with armor spam. While finesse can help with team bossing and general elite clear. This makes your stimm longer, and it still is/can be used to pull the ult off cooldown, however you will get both less often.  The stimm itself however will now have a notable damage amp + team damage amp and armor shred effect (or finesse, which is headshot and crit damage) that will help in tight spots, or can even be combo'd with the ult for heavy armor situations. 

2) You can take the 5% crit aura instead of 10% damage, depends if you feel you need more crit or like the raw damage. Also depends on teams aura's etc. 

3) You can take the 50% cleave talent on the ult, and drop something like "the sweet spot" which isnt as much damage as it sounds (bottom left 25% weakspot dmg) This can be nice in h40 for extra cleave on the higher enemy density values. 

4) Executor can be swapped for Precognition blessing on the shivs, preference. 

5) Ranged weapon - really anything you like is viable, Needle Pistol is just insanely strong. If you rock something else, and dont end up using it as much as one would the needle pistol, you can drop the infinite ammo node (pickpocket, bottom left) and grab something else you like. But pickpocket really shines on needle pistol and being able to just spam infinitely and never pick up ammo. 

note: dump stat on needle pistol is correctly damage as it doesnt do any 'initial' damage or very little.