Help needed for painting rusted Marsden Mat (Perforated Steel Planking)

I prefer a dark gray as a base coat. In fact, the primer I was using was a flat gray, but that brand's primer has changed is formula and I have changed.  I now use a medium gray primer, then the dark gray (flat) base coat.  I then dry brush the rust in areas, and a little dry brushing of Testors Steel for simulating very recent wear in some small areas.

Thanks Don, 

Appreciate your valued input, I will go get a rattle can primer (as I exclusively use an AB) and give it a go on pieace of scrap wood. Thank you for the information again it is very helpful.

Damian