Thanks guys,
Mark,
production F-22 have a silver sheen to them. Knowing your background you can guess at its properties. I ended up mixing about five parts silver to one part grey to get close. Inside it looks flat dark grey. In the sun it looks much lighter and shines a bit. This is going to be fun to see in cloudy weather. Using this much metalic prevents me from airbrushing around the radius with out leaving a silver halo. Here are a few shots of the work in progress.