So after over an hour of testing every possible combination in simulacrum, including trying the other builds here, this is the only effective non-bleed one shotter (a little unrealistic to get several headshot kills in action, but I digress).

This does not require any particular frame or ability.

Aside from the mods above, I needed:

• all the vigilante set weapon mods on sentinel gun
  -Rank 5 Arcance Rage
  -Rank 5 Arcance Acceleration

Even without the arcanes above, consistenly one-shotted non-eximus gunners.

If you want to fire and forget, then go ahead and use Hunter's Munitions, I just wanted the one-shot satisfaction.

I don't have the corrupted faction mod, and I havent rolled the riven, so this could potentially be much better.