I've been able to remove raised spots of rust using a penny.
But I'd avoid a high speed rotary tool, like a dremel. You could very easily polish through the bluing.
There's also a product named Renaissance Metal De-Corroder that's like a museum-grade naval jelly. It's relatively mild and slow acting, but the advantage is that you have a lot of control over the decorrosion process, and it neutralizes w/ water. It'll remove rust from pitting and it stabilizes the surface to prevent further corrosion - though you'd want to apply a protectant as well, to seal the metal.
http://www.restorationproduct.com/mainproducts.html