If they don't die from the initial blast they will die from the slash procs so don't waste your ammo on dying level 200's.

Update:

So I modified the build slightly by switching out [Point Strike] with [Galvanized Scope]. 1.2 Mill to 2 Mill
Changing the "numbers" for damage. I was corrected by my friend on Xbox that you can indeed land moderate headshots with the KuvaBramma.
Apparently, if you can detonate the project using the alt-fire 3 meters above the enemies giving you a headshot.
So I called bullshit and tested it out in the Simulacrum and SteelPath Grineer survival. It works about 66% percent of the time out of 200 shots.
Generally meaning that you were at two to three stacks of Galvanized scope most of the time. ie. 200% crit - 240% crit.
I could have switched arcane Merciless with Deadhead but the headshots are not a 100% percent chance in order to make the weapon's damage feel more consistent.

Options:

[Point Strike] or [Galvanized Scope]. 1.2 Mill or up to 2 Mill
Match enemy types with the appropriate BANE mods.