So i am digging into formulas for calculating armor penetration of projectiles and i thought i would ask this community for aid. I am fairly new to this and only really know about the Jabob De Marre formula on a surface level.
Image from a quick google search.
However i have heard that De Marre is flawed and only works for full caliber projectiles, not subcaliber ammunition such as APDS and long rod penetrators such as APFSDS. Projectiles with internal cores such as APCR (HVAP) is also problematic etc.