Headhunter
 Veteran Build - Warhammer 40k: Darktide 

Go for headshots/weak points and laugh as your enemies fall one burst at a time.
 

Your job is to headshot heretics before they even come into combat range. Whether you are at the front, middle or back of the team you want to practice marksmenship and be dropping targets from all ranges with sharp 2 round bursts. Avoiding shooting regular mobs where possible and prioritizing special and elite enemies you should be able to keep the pressure off of your teammates as you advance through the game.

With this set up, decent aim and a bit of luck on damage rng you can be dropping Crushers in 3-4 trigger pulls with headshots in auric mode. 

Reapers are often 1 but usually 2 bursts

Bulwarks 2 bursts

All specialists and elites except plasma gunner and mauler can also be dropped in one burst with weak point hits. 

Surprisingly decent at crowd control when needed but at this point switch to the knife to bleed crowds out and also deal a surprising amount of damage to single targets with Damage over time bleed stacks. Also the knife is set up to maximise mobility for quicker movement speeds whilst also having a high stamina pool for longer runs and blocking attacks. While penetration is the dump stat you will seldom notice this as the bleed damage is very high and more than compensates the lack of 80 penetrative strength on single targets. 

Use infiltrate to quickly do objectives, restore toughness, revive teammates (infiltrate and no one left behind stack movement speeds when a teammate is down) get out of sticky situations and reposition to a more advantageous position

3 krak grenades can help take harder targets out if or when the situation demands it. 

Weapon customisation mod recommended for optics/scopes.
Long range scope prefered.