You know, they have kits for fire-lapping barrels by embedding fine abrasives in bullets; when the bullet is fired, it laps the barrel, smoothing out imperfections. (Not recommended for high-quality barrels, but if you've got one that's rough, pitted, or shot out, it can yield an improvement.)
Why wouldn't someone be able to do the same with brass cases? The amount of metal removed won't appreciably change chamber or headspace dimensions, but it seems that within a box or two, there's a good chance that any microstamp will be polished out. And it will look a lot like normal wear. (Hmmm . . . a Nevada-based business selling "Chamber Polishing Brass Cased Ammo" might be an opportunity for someone.
)