The Angry Shiv
 Hive Scum Build - Warhammer 40k: Darktide 

The purpose of this build is to have regening grenades while focusing on good crits and when things get heated,using the ability for a massive increase in melee damage and attack speed (which if sustained will also trigger the capstone which also increases attack speed and damage, turning it into a blender).
The survival of the player depends on frequent dodging, typically to the sides or pulling out if you feel yourself getting overwhelmed or flanked. Pushing can work to make breathing room, but dodging is the survival mechanism which underpins the Hive Scum class most. This build wants to get stuck into melee but not bogged-down in it. I've found kiting enemies particularly fun with this build.

The shivs are what make the build. The Mk.3 means heavy attacks offer wide-sweeping strikes great for mowing through groaners and chaff units when aiming at head height (extra weakspot damage helps here, but if you miss the head, the blessings will still put bleed stacks on them to either finish them off or make your follow-up attacks even nastier). This build doesn't aim for guaranteed crits every time, but a speed of attack which makes the good chance of crits enough to carry it.

The main use of this build is horde clear, but with the chem DoTs, and that the shivs in this build also help put bleed stacks on enemies, even carapace armoured targets like Crushers can take a chunk of damage from well-placed weakspot hits and die in a flurry of blows and accumulating DoTs. (If others in the team want to take on the armoured targets they're welcome to!). 

The ranged choice is relatively ambiguous. The build doesn't lean into ranged combat as much, but bonuses to things like crit chance and weakspot damage aren't unique to melee only, so if you have a ranged weapon you're comfortable with that can land those weakspot hits, I imagine the build will still work for you. The early talent choices in this build like increased swap speed and increase reload on Close Range Kills are in my opinion, good for any weapons, and useful for those moments you need to whip out your gun to deal with those problem flamers or snipers when you're in the middle of a melee rampage.
My choice was the stub pistols because frankly I enjoy them. They're accurate enough for weakspot hits and have an ammo pool that can last a good while depending on the difficulty you're on. A flurry of weakspot shots in rapid succession can usually still put down carapace armoured targets quick enough before they become a problem.

I find the Stimm choice relatively flexible, but I went for maximum attack speed and crit chance to help push the build further when the pox hits the fan. It has a long cooldown time, but I personally haven't felt stung by the stimms being on cooldown between high-intensity periods, but the Sample Collector talent should help speed up its recovery just in case.

At the end of the day, it's a matter of finding a build which works for you and some folks might find other talent picks more to their style (tldr; I'm not going to senselessly defend this build, it's just one which I've enjoyed and found works for me).