Havoc 40 Toothpick Karsolas
 Ogryn Build - Warhammer 40k: Darktide 

To start with, this build was made because the Slab Shield just doesn't click with me, but Pickaxe does. Since I'm losing a defensive option from not using the Shield, going with enough Damage Resistance with Toughness Reduction was my goal to cover the weakness.

So I cleared Havoc 40 with this. Weapon of choice is Karsolas. It's my weapon of choice thanks to its ability to clear horde with its Heavy Attack combo coupled with the added bonus of having high enough damage to really hurt Elites. It also has a hidden Heavy Overhead Attack via Pull Special Action which can kill most Elites in one go, and by the fact it can also hits Bulwark through his shield if you angle it correctly. Choice of Blessing is Thrust for added Heavy Attack damage, which I do most of the time, and Wrath for extra cleave for horde-clearing. The higher havoc you go, enemies got buffed with higher hit-mass apparently.

Achlys Heavy Stubber is picked for the fact that it has high damage that can end most Elite in one headshot. It takes time to get used to for me, but the pay-off is high once you're used to aiming for Elites' head. Substitute for me would be Rumbler, but it has a problem if the enemies are too far. Also by the fact it bounce on most enemies. Rumbler does superbly well against Reaper, and do stagger annoying Elites for your Pickaxe to exploit.

For Talent, it's pretty straightforward. Reason why I go Steady Grip instead of Lynchpin was mostly to handle gunners in general. Frag Bomb for blitz, it helps when things go FUBAR, or for rescue. Indomitable is versatile thanks to the fact it can be used as a CC tool, a fight opener, helps you with ending high-value target that's covered by a bunch of mobs, or just opening the way for you and your team. Pulverize is there for Bleed, and the fact it synergize well with Delight in Destruction. Batter also synergize nicely for obvious reason.

Talent nodes that can be dropped are probably Implacable if you felt like you had enough damage reduction, or Strongest if you don't feel like gaining lost stack of Feel No Pain via a push is that valuable. I usually drop Strongest node for +25 toughness node or Attention Seeker, but I cleared Havoc 40 with it cause I forgot. +25 Toughness node is nice to have tho, since at Havoc 40, my toughness was at 98. It's redundant however if you can get golden toughness from your team, in which case Strongest do shine for survivability. You could also help your team by taking Attention Seeker, which helps taking enemies attention away from them.

EDIT: For curios, if 3x 17% Toughness is too much due to diminishing returns, you can definitely swap one for 21% Health. In regards to the curios perks, if 3x Gunner Resist is also too much due to diminishing returns, you can swap one of it to any perks of your choice. Few good perks are 15% Corruption Resistance for Blight Spreads modifier, 5% Health for small extra tankiness, or even 20% Sniper Resistance if snipers are pesky for you.

Outside of build, you should definitely play this kind of Ogryn as if he ain't a tank. Always engage near cover with enough space to manuever since any sort of gunners can melt you even with all those resistances, and funnel enemies to maximize your Pickaxe high cleave. You should also learn how to use the Indomitable well, since it could be a double-edged sword. If you overextend, it could end you. Underextend and you might get stuck with nowhere to go. Imo, my highest target to charge would be any variant of the Flamers since you can charge through when they're flaming. Gunners are also worth charging into, but that's if you have enough toughness and they're not all shooting at you. As usual however, assess your surrounding first! TL;DR Melee like a Zealot, Range like a Veteran, and be cautious like a Psyker.

All in all, this build is usable for Ogryn on Havoc 40. There's definitely better class, builds and all than this to clear Havoc 40 though, but if you're looking for a challenge, or just masochistic in general, this is the way. Or one of it anyway.