Meant to be used with [Garuda]'s [Blood Forge] and seeking [Talons], preferably with Xatas whisper subsumed. Pure damage build. Since bloodletting reloads instantly, there's no need for reload or magazine mods. There's no need for projectile speed mods, since dual chamber already gives a flat +100% projectile speed. Ammo mutation is used instead, as the [Felarx] becomes a serious bullet hose at 5 shots per second with an instant reload.
[Xata]'s whisper, incarnon weapons, and seeking [Talons] have an interesting synergy, as xatas double dips Attrition for 441x damage, then Seeking [Talons] makes a splash proc that scales off that multiplier. Furthermore, since [Xata]'s whisper scales off total damage, it can be used as a means to increase slash damage with elemental mods.
Evolutions
Attuned accuracy - +40% accuracy while aiming
Dual Chamber - +100% projectile speed
Wracking Wrath - +20% status, -10% crit chance
Devastating Attrition - 50% chance for +2000% damage