Here I am back at my old computer and noticed that not even the Weapon Model gets updated.
Here a Screenshot
http://i.imgur.com/OeFfsCO.jpg?1

Okay I am now Playing on an other PC and the Bug is not there anymore so the Bug is temporary fixed ...

Yes I where searching this problem everywhere.
I reinstalled it again and verified integrity of game cache again and it still does not work :(. Graphicscard and chip couldn't be it because it is a problem with the gameplay (inventory) and not a Graphics error....
Lets see if it fixes itself...

I will come after newyear back to my hostfamilie (where I still have my laptop) and will test if it is still there... if yes it must be a Problem with my account. Does anybody have any Idea how to fix it ??

But still thanks for your ideas how to fix it

It does not work