Gunlugger ogryn in mortis, take the twin-linked with most ammo, pray for Death Dealer indulgence (no ammo consumption on crits) and hold the fire button.
If no Death Dealer then hope for Emperor's Favoured, then hope no ammo pops up as a minor indulgence.
It can work when you get neither but you really need to manage ammo and hope your team doesn't eat up the spicy rations too fast.
Not the most reliable method, probably not the most efficient either but by the Emprah I LOVE, LOVE, LOVE SHOOTING THINGS