Its best to ignore crit damage and single target dmg.
Try getting Ricochet upgrades for the minigun as fast as possible.
Passive abilities Demolition and Torch for dmg, so that the bouncing shots can all trigger fire and explosives.
You definetly want the first Arsenal upgrade aswell, for the +30% global dmg, and upgrading it to get heal is also quite usefull in general.
And then just, have fun, the start is usually a bit tougher than with a second gun, but later its also easy to get the 10k achievement with this build
Will also Grant "Bullet Heaven" Achievement
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