When you say "the safi gun" I assume you mean a Sticky 3 Aquashot build but the other Safi LBG's are, for the most part, top class for each ammo type. Bowgunning is usually about picking a single ammo type you want to specialize in and building a set around that.
Sticky 3: Aquashot
Spread 3: Drakshot or Blackwing Bowgun II
Spread 2: Frostshot
Pierce 3: Aquashot
Pierce 2: Boltshot
Normal 2: Drakshot
Thunder: Adept Stormslinger (PS4 only) or Boltshot
Fire: Hellshot
Water: Aquashot
Ice: Frostshot
Builds:
https://imgur.com/a/EtU0FXU
Hope you have plenty of Safi mats hanging around.