since identity: every headshot (no need to kill) gives you a crit shot.
Put switch to crit bullet on another button then, I have scroll-wheel down for special.
The damage is alright, but I headshot ennemies fully charged and they survive. My aim is merciless, that should help. Also it might be worthwile going a bit for exterminator.
Right now I enjoy Doldren with Bloody Mary a bit more for such gameplay.