Hi all,
Here's another major iteration on the damage model with a much more advanced approach.
Should fix most of the inconsistencies of the previous version.
Overall this update provides a buff to high calibre and muzzle velocity cannons, with the addition of overmatching.
This update's for the 0.2 alpha, you'll have to opt-in to play it:

Changes
- Shells now simulate overmatching. This is when the force required to redirect a shell becomes higher than the plate can resist. With enough energy, projectiles will start to ignore the slope of the plates they hit. Realistically, this will only be a concern with plates thinner than 30mm. This effect drops off significantly at an impact angle above ~80 degrees. You might want to rethink any 5mm roof armour...
- Shell deflections now create spalling.