Already discussed this gun with chapmen on the phone. I am a little bit puzzled too. This "Leue" action was certainly made in Zella-Mehlis to Leue's design. But it's workings resemble no other falling block action known to me. It is related neither to any of the British falling block designs, nor to the German actions mentioned by Raimey. Note the unusual lever to block linkage by a crosspin riding an oblong hole and the inline striker or "hammer", powered by a coil mainspring, which hits a firing pin inside the breechblock. I know of no other falling block design that predates this rifle, 1913, showing even similar features. I know about another such Leue rifle in the USA.I emailed the owner to provide photos of the proofmarks on his gun. I have not yet found a patent covering the unusual action features, so further research is needed.