Hey, cool work bro, here are the crits.
Random/Unrealistic Wear
When doing metal, which is what i take favour in doing, is to really think out how the metal is going to be worn down. And with what you have, you seem to have overlayed a lot of grunge brushes, that cover most of the texture, which creates scratches that continue over the protruding struts/edges, when in real life, if something knocked into it, most of the contact would be with the sections that stick out most, while leaving the harder to reach places less damaged.
And the other major one:
Quality/Muddy-ness
Many areas, especially along the edges, have brushes applied that are either low quality to begin with, or have been scaled up to much, and are very blurred. Because of this, many areas are hard to read, and come of muddy, so i would suggest sharpening them up.
Specular
Dont be fooled by it. Specular maps are probably the hardest thing to get correct, often they take me longer than the actual diffuse to make, go back, and really work out how each of the materials will react to light, it will really sell the texture.
Good work man, keep it up.
