I have to admit I had not noticed a problem with mass driver penetration.
The couple that I did I didn't see anything outrageous for example a TL8
5cm/30 Mass Driver gave me a penetration of 275/265/255/235 firing APFSDSDU
this seems reasonable to me given that Twilight 2000 v2.2 (this is the one
that's supposed to be fully compatable ith TNE) gives the M1A2 frontal
armour of 120 on the turret and 200 on the hull. So this MD gun could knock
out an M1 at short range and damage it at extreme. Perhaps the problem gets
much worse with larger calibers? Or later higher velocity MDs?
Antony