Been playing nightstalker for awhile because of its orb output, but i've gone back to my roots. So, I'm posting a summary of my current build as a gunslinger when i want to play a little more team oriented. Here are some guidelines.
Equip either SGA or Thunderlord.
Equip a Hakke surplus sniper.
Equip boots with +LMG ammo
Equip Skyburners Annex (find one with 'inverse shadow')
Turn on Chain of Woe and Gunslingers trance.
Equip an artifact that spawns orbs on solar/arc precision kills.
*Exploit Celestial nighthawk or Archliophage Symbiote through armor switching
In my experience, this setup highly rewards getting lots of heavy ammo kills quickly. The gunslinger subclass perks will make all of your weapons shoot and reload like mega lasers after you've cleared out a wave with your heavy.
I would also emphasize the importance of using lots of heavy ammo synths, because you will essentially be turning all heavy ammo into orbs for your allies.
*You can switch helmets mid-battle to the nighthawk or the symbiote depending on your intent to do damage (deadeye) or create additional orbs (combustion), all without losing your super charge.
Switching helmets may seem unnecessary but it definitely adds to youre lethality. Rather than wearing nighthawk or symbiote constantly, switching to skyburners in between supers contributes to overall higher orb/super effectiveness of the team, and takes no longer than hitting a heavy synth.
Finally, to sum up what I've come to understand using this build: the gunslinger is uniquely equipped to take advantage of a strat that employs large volumes of heavy ammo. The class multiplies the lethality of precise exotic heavies leading to increased ammo efficiency. By using this build i've increased my kills per life, my orb output, the speed at which i regain my super charge, and seem to have an inexhaustible supply of heavy and sniper ammo at all times.