Just a Gimmick
 Zealot Build - Warhammer 40k: Darktide 

Perfectionist (Shroudfield node) is a flex point.

You can swap it out for the following:
- Riposte (more personal damage)
- Providence (more team-oriented)
- Anoint in Blood (Ranged damage will help kill packs of armour more efficiently)
- On the Brink (If you're worried about gas)
- Restorative Verses (if you're dying too easily)

Use bolter to break up dense packs of elites or to help kill/debuff packs of armour. 
Dreg ragers aren't too bad, just heavy swing into them. 
Scab ragers are just easier to range down with bolter.

When swapping to bolter, throw a knife to skip the animation and shoot faster.

Use weapon swap to reset your Thunderhammer charge if your timing is off, rather than using the special attack button to deactivate it.

When DH or captains are getting to their feet, don't wait too long because they'll whip around and you'll miss out on the backstab damage. You have about a MAX of 3 seconds from the beginning of the rest animation to standing/attacking.

Light attack strikedown are for elites.
You can also heavy swing to knock them over and then follow up with a quick light to kill. This works on every non-armoured mansized elite/specialist.