Taken from Yuri Pasholok's (WG historical consultant and tank researcher) blog.

"There has always been some complaining of "compromises" related to historical accuracy of German vehicles. Surprisingly, real German WWII research and engineering exceeds the boldest expectations.

For instance, Krupp's archives have the following inventory:

2959 15 cm K, Entwurfe, Berechnungen enthalt:
15 cm K L/40 fur [PzkpfW "Maus"]
15 cm KWK in Tiger II
7,5 cm KWK und 15 cm KWK L/38 fur Pzkpfw "Maus"
15 cm K L/38Patronen fur Pzkpfw "Maus"

And that's not all, however we are excited already."