OK, it appears I actually cracked the AP pentration code!
Once I realised the linear drop in penetration, I got my oldest son (who's a math whizz) to write me a formula where you enter the penetration at two different ranges and it will calculate the pentration at any other range.
Then I figured out the fractional role that warhead size plays, which was really the key to deciphering AP effectiveness. I remembered that SP design was influenced by tabletop wargaming, which I believe often used fractions.
Now I can instantly predict the base penetration of any weapon at any range, as long as I know the weapon's:
1. Max Pen
2. Max Range
3. Warhead size
I haven't tested it with sabot rounds yet, to see if any additional voodoo has been thrown into the pot, but I suspect that the extra penetration and differing ranges of sabots are enough, so I doubt there's more to them than that.
Then I'll try to make a penetration matrix or excel calculator that people may find useful.
cheers,
Cross