Both are now in 7x57. The first one was reproofed by the Vienna proofhouse in 1968. So it was possibly rebored and rechambered then. The other one was rebarreled outside Europe, most likely in the USA.
If you google Franz Neupert Wiener Neustadt, you will find links to several more Neupert guns. Here is a link to an “Ischler Stutzen”, that is a single shot break open, side hammer, full stocked stalking rifle: http://www.germanhuntingguns.com/archives/neuber-franz-wiener-neustadt/