In my model making I've always used Plasti - kote sandable primer (grey) for plastic, metal, and wood surfaces with great success and never any loss of detail even with a bit of over spray, it's just an all around fantastic primer. I don't know about now (because it's been a number of years since I used it,) but Testors Metalic paints came in various finishes, some for direct applications and some to be buffes to the desired finish,but you had to coat the steel color or it would actually rust.