I've had pretty good luck using Testors Metalizers. Many complain about their inability to hold a polish, and them darkening because of finger prints, but I haven't had that problem. I use the rattle cans instead of my airbrush, and for silver usually use "Stainless Steel" metalizer. It will polish to a bright finish, however I usually just buff it a little to make it look less like paint and more like steel.
This picture:
http://www.craigcentral.com/models/f-105g/thud04.jpg
Shows a nosegear I painted with it. It isn't finished; no weathering and I'll polish it some more once I get all the painting done, but you can see in the photo that it doesn't look much like silver paint. The same paint was used on the gun port right in front of the muzzle of the Vulcan and it really looks like a piece of aircraft aluminum.