I have come across old articles in several places speaking about a German double rifle and drilling action called the "Nimrod" but presumed that these were German variations on one or another British design. I recently found the Guenther Retz website http://www.buechsenmacher-retz.eu/index.php where he talks about reintroducing this action for the first time after it ceased production in the 1930s. I wonder if anyone knows what this was and would please explain its features here.

Thanks in advance and good hunting!