Have you ever felt like there are too many hindrances in the way of your glorious bullets as they tear their way through the enemy forces?
Have you ever felt like your bullets were too ineffective at their intended cause?

If the answer to either of those questions is yes, then I present you a solution in form of this simple tweak.

With this mod Surefire Aced (which normally only allows you to pierce the tan armor) now lets your bullets pierce Shields and thin (up to 40cm) walls. 
Body Expertise allows your bullets to pierce enemies themselves.

This is a BLT mod, just put the folder into your mods folder in your Payday2 directory.

EDIT: 
Mod was seen as too cheaty, I have implemented totally strict and really hard to disabled anti-cheat features that can't be circumvented to adhere to the rules like any law-abiding citizen would.

These really well thought-out anti-cheat measures that cannot be removed without dire consequences are as follows:
Pub games and achievements are blocked when using this mod.

Jokes aside, if you do take out the anti-cheat measures then you may want to host your own lobby, running LMGs with BE and Surefire aced trivializes shields and packed clusters of enemies on any difficulty.

The only idea I'd have for balancing would be to replace the second level of Body expertise with these effects, netting you a 60% decrease in potential damage in exchange for this.