Paul,

Theo Jung and Dirk Brinkmann designed the FZH actions from what I know, and virtually any configuration you want is available from them. As an aside (the experts would know better than I do what the advantages - real and perceived may be to this) they claim to follow the hardening routine that was originally used by Mauser and DWM in hardening different parts of the action to different degrees in order to make them work more smoothly.

Stuart Satterlee's website has been dead for a while - no idea what is happening with his business. He did seem to have problems as a long argument with him on AR some time ago seemed to suggest.

Good hunting, my friend!