Looking at a German Cape gun with a barrel in 12-bore x 2 1/2 inch and a rimmed barrel which is approximately 11 mm calibre and a length of approx 38 mm.

Gentlemen

What cartridge do you think this may be?

Thanks.

Nitro,

What about the 11m/m pistol, German Service round?

CoTW list:
bullet dia. - .451"
neckn dia. - .449"
base dia. - .453"
rim dia. - .509"
case lgt. - .960"
col. - 1.21"

This is the only thing that I could find close to your dimentions. A chamber cast would help, to get a better ID.

Hope this is some help,

Hog Killer

Could be a Werndl or Vetterli cartridge; but neither appears likely. Possibly a Früwirth. See also the following list:

http://www.municion.org/iphp/gr.php