Outcast Gunlugger - Fitz's H40 Tested Builds
 Ogryn Build - Warhammer 40k: Darktide 

This build is practically what Outcast Engineer does in VT2. The twin-link can easily decimate bosses like Rodin in Spillway even in H40. Basically, you never use the Twin-Link outside of your PBB. Treat it as part of your ability, just like the gatling gun is for OE. There's another version that uses the Rumbler for fire + brittleness. Just swap some nodes around for "Fire Away". A third option is the Blaze Away Kickback with Hail of Fire, instead of Light 'Em Up.

Here's the main issue with PBB Oggy in the current meta, anything and everything will knock you out of your PBB and then you eat a 60 s cooldown. If you don't like that idea, best not to run it. You're also not a frontliner, so you need another oggy or a arbi to help you on that front.

As for melee, it doesn't really matter in this build. Much like the ripper gun toughness factory, the Bully Club is just here to regen toughness when you find yourself in melee. Haymaker is still pretty fun, but skullcrusher or thunderous are probably valid.

Blitz shown here is Frag Bomb because the TL Stub can take care of most ranged targets, but if you still miss the Rock or find mutants annoying, then swap back to it. Again, Frag Bomb is highly valued in Heinous Rituals or other events/modifiers that need AOE clear.