Hi,
there is an excellent book on the Kuchenreuter dynasty (although in German):
Die Kuchenreuter und ihre Zunftgenossen by Dirk Götschmann
There is also the Kuchenreuter family chronicle available online (in German as well):
http://www.kuchenreuter.de/datei?datei_id=2
Of course, there are other books available, covering in part the Kuchenreuters' works.
Are you collecting the guns of Johann Jacob? He is one of my favorite gunmakers...
Regards,
Matus