Unlimited Defence Budget Veteran
 Veteran Build - Warhammer 40k: Darktide 

This build has been tested on difficulties up to and including Auric Maelstrom. During this testing I have not run out of ammunition even a single time (and I didn't pick up any ammo boxes). 

This is a sustained DPS backline build which focuses on removing entire maps of specials and elites with a ridiculous amount of crit-weakspot hits. It is not really a 'sniper' setup, as it focuses on the weakest of helbores for the best ammo economy, so missing shots is not the biggest deal -- continue firing at enemy outlines and you are bound to hit something. 

This build might have a somewhat counter-intuitive set of crit sources, being Surgical and Deadshot, however it's a piece of redundancy that simplifies setup and allows you to focus on rapid gunnery. Basically, an ease-of-use pick.

But it works wonders in matches, allowing massive ammo conservation during normal gameplay -- if you can see it, you have the shots to kill it.

And on the topic of seeing things: Executioner's Stance is not Shout and therefore already making this build a somewhat offmeta pick for the highest difficulties. But you can shoot pre-spawn bursters through doors and pixelpick trappers through hordes -- so we're not talking about an entirely selfish build here. You can and will eliminate some of the most irritating enemies from very long distances, making them a non-factor in any current engagement undertaken by your team. 

On the closing note, feel free to just shoot things. No Respite is an amazing blessing for dishing out big numbers, and you do have enough cleave to hold back a light horde.