I did use the GW washes on these, three different ones in fact. What's hurting the metals the most is the photography. This guy has been hit with Testors Dullcoat and still looks shiny (especially on the pelt). I'm not sure exactly what the problem is. I don't have a light tent, but I did use three different light sources. I'm currently shopping for a light tent and when I find one I may be re-posting this guy along with others I have done recently.
The face is good and the pelt works well. But your metals need some work. have you tried the new GW washes? They are excellent for metals (and most other things as well). Sven