Hi,
I came in contact with a guy in Germany via my oldtimer club connections.
Apart from providing cars for film and tv, he also specializes in renting weapons for the same purpose. He also trades collector's pieces and has some nice material on his gunsite. These include some rare target versions and a couple of unfinished (in the white) late mauser parabellum versions.
The site can be found at:
http://www.teuto-arms.de