Also worth noting that the CAD work and the animations are actually separate functions. The cutaway gun you linked to could be done entirely in an animation suite, and trying to animate something with that many dependencies in even the most advanced CAD programs on really good computers tends to fail/bug out. You either have the part files and an assembly file for engineering and manufacturing, or you're animating it to demo/sell. They don't follow one another easily.
ETA: I do CAD/CAM work professionally, but I am not a dedicated CAD drafter, nor am I an animator, so I don't know if I meet your requirements of "high end" CAD drafting. Experience in AutoCAD, Inventor, Mastercam. I'd be happy to sign an NDA and take a look at what your friend needs done to see if I can bid it. PM me if you're interested.