Zealot: auto-reload, quick swap Boltgun
 Zealot Build - Warhammer 40k: Darktide 

This build is focused on melee but it still has a very high DPS Boltgun that is quick to swap to and always has at least a few shots without needing to reload it all the time.

Read below for tips and hidden features of Talents and Blessings.

Auto-reload from Out of Pocket makes it so Boltgun is never empty for long, and you don't need to manually reload it while there are enemies to kill in melee. However, notice that it says 10% of missing ammo from mag, not max mag, so it will reload fewer and fewer bullets the closer it is to a full mag, but it can still be fully reloaded overtime since the progress to the next bullet is saved, even if a single kill would not round down to one.

There is a bug with Out of Pocket currently though, at least with Boltgun, if you start manually reloading, but then interrupt it and get some melee kills and add a few bullets to the mag, you will still have to fully complete the manual reload before you can fire again. So watch out for it.

Quick Swapping to the Boltgun works like this:

Swap to Boltgun > throw Blades of Faith > start firing or aim down sights instantly

This saves about a second or slightly more. Not so useful on Flamer since the issue there is the aiming animation not the swap.

The melee weapon can be anything with good attack speed and high mobility, such as Assault Chainsword, Tactical Axe or especiall the Shock Maul with Skullcrusher. Unless you switch away from Chorus of Spiritual Fortitude to the charge ult instead, so that you can use Eviscerator or Relic Blade. But then you would lose the bonus boss DPS Chorus grants to your team and your Bolter through Ecclesiarch's Call.

The best is still Maccabian Mk IV Duelling Sword, of course. But maybe Munitorum Mk III Shock Maul could replace it, as it has some quick combos, can open Bulwark and interrupt Crusher Overhead with the Special.  

Cleave Damage is the dump stat for Dueling Sword because it does not decrease cleave targets only damage dealt to targets beyond the first, and not by much.

Finally, Rampage blessing on any melee is not just damage as it claims to be, but a Power multiplier. As such it also boosts cleave and stagger while the damage boost is multiplicative with all others we already have.