Specialist Hunter Vet (H40)
 Veteran Build - Warhammer 40k: Darktide 

The targets that this build aims to kill (Flamers, Bombers, Trappers) are dead in one body shot (Some heat buildup can be needed for flamers).

Elite gunners are killed in one weakspot shot with enough heat buildup

Thrust in combination with Maniac Damage are taken on the Dueling Sword for mutant weak spot one shots

It is also very good in combination with Uncanny Strike for Crushers, Maulers, Captains and Twins while being decent at killing Monstrosities.

Perk wiggle room :

Rending Strikes or the Toughness Boost  next to it can be skipped if you want to take another perk instead
Fully Loaded can be skipped if the team is not using a lot of ammo. You will need to refill more since ammo boxes will give less
Field Improvisation can be skipped for Withering Fire if nobody in the team uses grenades and/or has a form of corruption regeneration, but i feel like the gain is very minimal and usually not worth it.

Depending on your play style, the bottom right side of the tree (Exploit Weakness Desperado Skirmisher Reciprocity) might have more or less impact. I still think that these four perk make the DS one of the strongest single target weapon, allowing to kill crushers, maulers and twins very fast . Skirmisher is also very important for plasma gun breakpoints.

Good perks to take if you have spare points :
Trench Fighter Drill Iron Will Born Leader Agile Engagement Leave No One Behind One Motion, any Toughness Boost or Toughness Damage Reduction 
Special mention to Stamina Regeneration Boost, which allows to sprint infinitely and dodge incoming fire without running out of stamina by doing heavy1 into slide with the DS