[PlasmaKrab]

Guys, are we still talking about the "Das Reich" mod? If so, and assuming I have understood anything to the storyline, there would be no Hitler to heed the Imperial decisions and ruin the whole business in a few years, right?
This and the rest being considered, I agree with Marcello that four parallel tank gun calibers are overcomplicated. Now how about using them as two parallel runs, each one evolving over time from one caliber to another? Say, start with 105 and 150 as main weapons, respectively for light/medium tanks and light TDs and for heavy tanks/Stugs. Meanwhile, keep the 128 and 175 for seldom exceptionally heavy vehicles, and later on switch them to main calibers, while developing new ammo for them.

There again, I'm not sure there is much point in such large guns once you have better technology for AP rounds (make that the 60s, I don't know the technical development line you have in mind).