Hi Hubert,
Sorry but I can't offer any advice on the Vienna mount system as I've never handled a rifle with that type of mount.

Usually one of the most important things with any QD scope mount system, is to ensure that there is no stress or flexing of the scope or mounts when the scope is installed.
The mounts should snap into place freely with no looseness or movement, but at the same time with no springing or flexing of the scope tube or the mounts.

It looks like "kuduae" might be able to help with the information you need.