I've done some wet sanding on aluminum before on my RC cars and started with 400 grit sandpaper to get all the grooves out and some deep gashes. Then moved up in grits of sandpaper all the way up to 2000 grit and then used some Mothers polish. You can get it to the point that it almost looks like a mirror. I may have to buy me an extra barrel shroud and see what I can do..lol. This was a great idea.