My pleasure... always happy to help another Brnophile

Unless you absolutely MUST have an original ZKK scope and QD mount for a collection (and they are not without some annoying traits... including the lack of precision click adjustments and the subsequent amount of ammo needed to sight one in!) why not look at alternatives?

Someone based in the EU has manufactured a range of new QD mounts to fit the ZKK600 and the CZ550... available in two QD configurations (one with conventional small levers, the other with curved spring assisted over-centre levers that are less likely to catch up on clothing or gear.

http://www.ebay.com.au/itm/Super-Quick-R...=item23276837d4

http://www.ebay.com.au/itm/Quick-Release...=item23276837de

Maybe they will also offer QD mounts to fit the shorter ZKK601?

I originally thought they were made by MAK in Germany, but perhaps one of our EU-based members can clarify?

http://www.kilic-feintechnik.de/en/scopemounts/scopemounts/?tt_products[cat]=16
http://www.kilic-feintechnik.de/fileadmin/pdf/MAKuick_SSM_-_CZ550_Englisch_-_Datenblatt__1_.pdf