yeh, unfortunately, all they repro now in the magnum 500s is either full chrome or full painted. The only way possible of dulling them down would be to maybe use some light steel wool but even then I would be worried that it might totally mess it up. From what I have heard, there still are companies that do the satin chrome but it is a weird process. Something to do with the chrome being "dirty" and therefore coming out that way or shine.
Your only other option is to find some good used originals.