There are a number of styles of swivels in the "Rifle Accessories" section of the Recknagel catalogue download.

There is also an Australian agent for Recknagel, who gets regular deliveries. Graeme Spraggon in Tamworth, NSW. If the contact details on the Recknagel site are out of date, he advertises on www.usedguns.com.au in the parts section.

For any one who does even an occasional rifle build, I would highly recommend that you get the Recknagel print catalogue.

Some serious drool material in that, and it's gratis, and sent promptly.
http://www.recknagel.de/Joomla/en/catalogues/print-catalogue-order.html