I would have to agree, the "damage" model has never been too accurate in AH.
Maybe on purpose, maybe not. I don't think back in WW2 the tanks engaged each other at those distances, I could be wrong.
I know artillery lobbed shells a long way, like the 88's and 105mm guns, but that was usually at a larger target like a city or fuel/ammo dump.
I would love to see the GV's in the game operate more realisticly, however I feel most would complain. Again, I could be wrong.
Osty rounds are not proximity fused rounds