i played a couple games with headshot in scout in 0.8.7, but no wins - the closest i got was somewhere in io, after opening up a door i was greeted with fast exalted reavers in my face, and while i was able to bring two down, the last one killed me
i have yet to play around with the mechanics of gunslinger, but it does seem on the surface like dualwielding revolvers would be untenable rather quickly. however, two unmodded 9mms would be enough to oneshot formers, and after the frenzy bonus kicks in, you should be able to bring down larger enemies without much trouble. a revolver (ideally adv in damage, but building to a P3A standard should be fine too) would be good in the third gun slot after you take gun hoarder to save for emergencies like armored ravagers, exalted melee enemies, etc. once you get into io, it seems like the logical choice would be to just ditch 9mm altogether and throw everything into two plasma pistols