Tested alot of different variations here : But Apparently [Hellfire] + switching the toxin mod to [Malignant Force] gets us at 120% perfect shot Status chance gives a 20% chance to apply a second status & the 90% heat off Hellfire Makes the status prority become more heat based and makes this setup is actually competetive against Bladed Rounds / [Galvanized Scope] & Primed Faction mod.
Baseline Competetive & actually goes ahead in dps when u factor in the 4. Status coming off heat + Galvanized Aptitude scaling.
Getting a Riven with Heat + Multi & crit / cdmg & negative puncture or magazine / zoom would be pretty insane here.
You can also Play [Terminal Velocity] in Exilus Slot if you move the exilus polarity onto [Critical Delay]. But I think the Double Vigilante Mod combo 10% chance to get another free crit Tier is pretty sweet.

Galvanized Scope is 200k Ahead with max stacks up, but u wont have these up 24/7 so its a more inconsistent option but still stronger in a perfect scenario.
Though I think its nice to have the heat behind on this as it synergizes well with viral + scales [Galvanized Aptitude] & reduces armor abit + the dot ticking mobs down feels good.

Arcanes are pretty optional : Primary Merciless has the highest dps output at 10 stacks, Downside being u need to get & maintain the 10 stacks.
Longbow Sharpshoot is pretty close & will work on bosses / acolytes , Downside Being u need to always hit the Head (which lets be real wont always be the case)
Primary Deadhead is also an option but requires u to always strain ur aim to be ahead of merciless. The upside of it is the 24 second duration from headshot kills % scaling, More general Uptime with less KPM.