At the moment, the list of penetrated(I hope i mean this right) surfaces \ walls \ things is extremely small - these are wooden walls \ wooden decor \ wooden roofs and floors. That’s all.
I suggestion few things.
1.All weapons should get their penetration characteristics.Now only anti-tank guns have different penetration characteristics, but all other firearms do not. The penetration characteristic of the nagant is equal to the mosin rifle.Its are absurd.
2.Thin sheets of metal must be penetrated by rifles and anti-tank rifles. Stone walls - tank guns (depending on the thickness of the wall and the caliber of the gun).
In general, depending on the characteristics of the penetration and thickness of the object, there should be a result - penetration \ non-penetration \ penetration with such and such damage and penetration with other damage.
Perhaps it is necessary to describe in more detail, but no. What do you think?