My "Honest John" [Kuva Zarr] build is meant to be effective in both forms, but if you're more inclined towards headshots then you can replace Radiated Reload with Galvanized Scope to increase you're burst dps to 2.15M - 2.96M at the cost of one additional forma.

With Arcane Avenger and Cat's Eye you can get this things crit chance up to 167.5% - 197.5% and the 1/20 chance on Vigilante Supplies means that you're gonna get 2 or 3 procs per shot with the barrage form's 42 Multishot so this absolute beast can also RED CRIT.