ManiK.
Try using the Gunmetal colour to paint the items first as you are now and allow to dry. Then dry-brush over this with a lighter shade of metallic paint such as Testors "Steel" or even just silver. Make sure you get rid of most of the paint in your brush on a tissue or piece of paper, the brush will seem almost dry, you just want a bit of pigment left in the bristles. Try to just get the dry-brushed colour to catch on the high points of the molded detail as you lightly pass the brush over it mabe a few dozen times,stop when you see the effect you want, this simulates the worn blueing and wear and tear found on heavily used weaponry. I think this is what you are tryingt o do. Hope this helps.
Regards....Snowy.