TsKIB of Russia makes, or made, a revolving shotgun in 12, 20, and .410. There's a link to an article in Russian, with pics.
http://www.kalibr.ru/mag/7/oh_re.htm For more info/pics google MTs 255 (or МЦ 255)
People who used them say they work.
+ Instant selection between 5 different loads, good balance, accurate with slugs (in sindle-action mode).
- too heavy for the gauge, trigger pull in double-action mode way tpp heavy and sloppy.
Never held one myself, above is just a summary of what actual users posted on Russian gun boards.
