When I import a character, gun or anything from blender parts will appear to have a yellow brown solid color, or a tint that can be seen. Here is my model seen in blender
There is also a transparency effect on the lens too, but that doesnt work in unity like it should. Also, shades dont show up. what should be chrome silver is black.
I would do my stuff with blender internal materials, check that faces are not double sided, normals are the right way, remove unused materials, only 1 uv map per object, no node stuff.