I used .005" shim stock. If your gun is properly made, there should be no need for doing that. The only reason I noticed that I had a problem is a buddy wanted me to lap his 454 SRH, and I decided to do mine at the same time. His rings were dead on, and really didn't need lapping. If I hadn't shot my gun so much to know how accurate it was, I would send it back, but since they'd have to replace the whole gun to fix the problem, I'll live with it.
The target gray finish will wear with use. I carry my 480 at least a month a year in the field, and it shows some where here and there. Since it's stainless underneath it isn't a problem.
Lapping the rings is easy. You install the rings on the frame with the top half of the rings removed. You can use a piece of 1.00" round stock with 180-240 gr lapping compound, or get one of the commercial kits. I put a bit of layout blueing on the ring first to see where the compound is cutting. With that set, it is simply run the lap back and forth and check for progress. You don't need to get 100% of the layout blue off. If the blue is coming off from the front and rear of the ring, you'll know that they aren't canted. Once ~50% of the blue is off, just clean up the grit with a solvent, mount the scope, and go shooting.