Brownells has a page with various parts source for some obsolete parts and their tech line is always a great help.. Mauser firing pins should be fairly easy to find. The Winchester butt stock should be available from many of the custon stock places such as GreatAmerican and Boyds.. Others may be found in the pages of GunList(GunDigest now). Also don't overlook EBay,, They are still a source for those parts they don't deem 'dangerous'! They may also have some of the other parts you're looking for.. Brownells can help with the magazine parts for the '92..