This big bore breech loading percussion rifle was just way too cool, I thought others might enjoy drooling as I have been.
http://www.collectorsfirearms.com/german-elephant-gun-al1339/

Bore is listed as .955", so inbetween a 6 and 5 bore. Only place I've seen a breech like this one was on a cannon. But then again this is just a man portable cannon.
Sad I don't have $10k to buy this super unique piece of art.