If those weapons exist in real life, anyone will have a hard time proving that you traced them from games, instead of actual real life weapon sale promo material from the manufacturer. Speaking of which why do you not use material of the real weapons?
Viewing post in "Copyright" or "Transformative", "Fair Use"?
Uhm. Now that I think about this, is this allowed? Are there any legal issues with having a known real world item be converted into digital as an asset? Do the makers of CoD and others pay some license fee or whatever?
It might be different for movies, where you would simply take the real thing (maybe not weapons) and have it as a prop. But as it can be seen as advertisement, most movies refrain from that (apart from product placement of course).
If you are tracing them anyways and it is an exact replica, meh. Depends how legal tracing is, if you traced copyrighted material. There is a grey area that is called referencing. But if those weapons are "free", you can bet that there are 3d models of them available.