There is something wrong with explosives and acid

Devs really need to check what is going on after hitting with explosives and high damage weapons. Just a moment ago I had situalion when my Hel Cannon took out 50 armor from Siren. 30 from torso and 20 from one of the arms (was in one line behind torso), also did 150 damage to torso.

How is it possible that it took out 30 armor from that torso? My heavy is single class and didn’t took any perk, so clearly there wasn’t any possible bonus. I have no research of Siren autopsy, not to mention vivisection. None of the soldiers fired at her before that heavy first shot.

And how it took out 20 armor from arm if it wasn’t even scrached with damage. I know that Hel can pierce through objects, but clearly damage was negated wholly by that Siren torso, so projectile shouldn’t go beyond that torso.