Seriously just try this. It's insanity.
 Hive Scum Build - Warhammer 40k: Darktide 

Are you looking for a comfy hive scum build?
You want to play a melee focused Hive Scum build?
 This one will blow your mind for it's unicity, damage output and damage upkeep, and unparalleled survivability (at parity of skill level of the player that wields it).

This build presents oddities within it that are, however, easy to explain.

The blessings and perks on the needle gun don't work on anything but on the needle impact, while most of the damage it deals come from the chem dot damage. So it's your way to deal with crushers and bulwarks mostly, or! Far away dangerous enemies such as snipers or bombers. On top of that you have 16 stamina bars. S I X T E E N  with your needle gun out. Which means, that as much as you sprint you are basically immune to ranged attacks as you had Desperado active. Because your stamina is endless and there is no other way to put it.

Since ideally you use chem to deal with crushers, why would anyone put +2 stamina on the crowbar. So you can have 18 stacks of Swift Endurance while swinging it. It's so ridicolous that you one shot most enemies anyway, you are a damn blender, even without rampage active. You are basically immortal as long as you deal well with crushers and as long as there are living chumps spawned.
The crowbar is my melee weapon of choice as it's hive scum's most versatile melee weapon and possibly its most accessible way to kill crushers, for which you should generally pick Can Opener, but you will use the needle gun for them if possible, or rely on your veteran that is. Furthermore it's arguably the most staggering HS melee weapon, which allows you to take advantage of the +15% damage against enemies that are fully staggered. Though I am not sure that the wording is correct on that node. Does fully staggered mean that an enemy has been thrown legs in the air, on the floor by a veteran shout?

I honestly think that the double shivs are also a very valid option though, especially with bleed on them, unfortunately I don't think you are able to physically click as fast as you could to have the damage output that such attack speed generates. Try it, put +2 stamina on your shivs, put all the stimm points in attack speed, pop your ability and see for yourself what kind of emperor forsaken blender you become.

Chemical dependency is currently the best keystone (even for ranged builds) and the idea is just invest from 1 to 3 points at most in the stimm lab so you can have it online as long as you can. It's easy, and with any cooldown of the stimm under 26 seconds is easy to mantain.

Chem Grenade as it is the objectively best Blitz in the game at the moment.