Generaly speaking, this is not a request board, so you know for future reference... but I got just the stuff for you:
If you go here.
LINK
You will find in the list of model packs two downloads labeled "Modelpack 5" and "Modelpack 6".
These will hold a whole set of high quality (especially MP6) weapons complete with animations. Not only that, they are also designed for FPSCreator which has a very similar set up to GG. So the tweaks you have to do will be minimal.
If you tweak them, you can orientate yourself on the gunspec files of the stock GG weapons. to get them ready for shaders, I've written a tutorial on how to do that
here.
Don't expect to find entire packs of animated, rigged, functional weapons for free often. In fact, I don't find that these should just be able to download like this but they are.
I attached 2 preview pics to this post.