I looked at your site and checked out your models, which are very nicely done I might add! And I can indeed see what you mean by texturing issues, in terms of resolution. In some cases there, I don’t think it’s resolution that’s hampering you, but the UV layouts you’re using rather. Check this one out, for example:

In your map here, there is a great deal of unused space. The wood areas could utilize this extra space especially - metal shaders can often get away with less detail and more material/shader “tricks” and settings to keep them looking metallic, but I think considering the surface area of your model being mainly the wood grain texture, it would help to have more UV area for those parts.
Here’s a quick example of how you could go about making the wood texture higher in resolution and therefore cleaner at rendertime/realtime:

Now all I did here of course is move stuff around and resize the wood parts in Photoshop. You’d want to redo the wood parts at this resolution to make them cleaner, I’m just showing you this as a concept of how to increase the already available resolution of certain areas.
Hope this helps a little!