This is what Matt Firmani said before:
"When reported, we already take action against copyright violations and inappropriate models (sexually explicit, firearm models that actually work when 3D printed). We have chosen not to take the extreme measure of removing all firearm models from GrabCAD, as firearms are impressive engineering feats, and for some, they are a lifelong hobby and passion. But we require that these be non-functional, and it's on the uploader to provide proof that this cannot be used as an actual weapon."
Also, GrabCAD's Community Values and Guidelines include this:
… upload deceptive or incomplete work. If the CAD files uploaded are different than the images, or there are no CAD files uploaded, or just the CAD assembly without the part files, we may take the model down. And if you post a question or tutorial that is incomplete, we may take those down as well.
Now when I want to upload a model of a gun, I'll have 2 choices:
How can we upload such designs without breaking any of those 2 laws ???