The 3X headshot multiplier has been introduced recently, replacing the old 2X. Primary Deadhead amplifies this further. Always aim for the head holding RMB or L2.
[Thermite Rounds] will provide some ease of use, as the enemy's "on fire" animation is smooth, and it overrides the Impact animation (needs testing).
[Hunter Munitions] is overrated, since it doesn't get through shields, so we aren't using it here. We are also not using it here because slash procs can't trigger a headshot kill for [Galvanized Scope]'s effect.
[Galvanized Scope] is a must, since it gives +320% Crit Chance, getting us to the tasty 117.6% crit chance at max stacks. To add even more damage, use the Vigilante mod set on your sentinel and its weapon.
In a riven, look for +Critical Damage (to replace [Vital Sense]), paired with either Multishot, Damage, Critical Chance, or Viral (as a single element). A negative is a must, preferably -Zoom, -Dmg to Infested, -Reload Speed, or +Recoil.