Let it scale to user penetration, not to target's resistants. For now, its just braindead procset.
Maxing pen doesnt boost ur surviability, like weapon/spell damage modifers boost sheilds/healing. It also requires investments in light armor to be maximized. So set would not be universal gun for everything and everyone.
And its users would be match the design of this set: focused on countering fat cans.