KwK 40 L/48 vs StuK 40 L/48?

[Crossroads]

The same gun aren't they? http://en.wikipedia.org/wiki/KwK_40

So why different weapon values?

I am of course talking about PzIV H/J and StuGIII G

Weapon data:

Pz IV H
P01665 28 26 24 22 19 16 13 12 11 10 9 8
11 11 11 10 10 10 9 9 8 8 7 7 6 6 5 5

StuG IIIG / IV

P01022 24 22 20 18 15 12 9 6
9 9 8 8 7 7 6 6 5 5 4 4

To add an insult to injury, here's PaK 40 ATG (L/46)

P01168 32 28 24 20 16 12 11 10 9 8
9 9 9 8 8 8 7 7 6 6 5 5 4 4

Whoah! Of course, the ATG had different cartridges, enabling a higher muzzle velosity.

Any way, back to comparing KwK to StuK. That's quite a difference. Why?

I don't think the gun was different. Just a different name.

Optics? I have not heard the optics were different. I have not found a statement saying they were the same either...

I am considering a new upgraded StuG IIIG unit for my mod, with PzIV weapon data. The assault guns are having a hard time against T-34/85s and IS-2s / ISU-2s...

Any reason why I should not do it?

EDIT: Hard values only, as the soft values should be different, PzIV was better armed with two MGs.

(Just to remind, whatever I do with my mod does not effect the EF2 stock engine or scenarios at all).