To remove consistancy errors you can delete the world models. That is if your not concerned about having them, you know. It shouldn't have them though, It didn't when I tried it. I guess valve must've patched css or something.
I noticed you posted a question in the message board for my P99 skin.
The consistancy error your getting is because the world model is reflective. Its a nice little feature I added but I didn't realize the consequences when I did it.
Its a simple fix though, just go to your cstrike folder, materials->models->weapons->w_models. Open the .vtm file in notepad and look at the contents. Replace the contents of the file with the following:
Then save the file and close it.
Now the game won't try to make the world model reflective. It should get rid of your problem.
Enjoy the weapon.