A while back I mentioned a late friend of mine whose Krieghoff Teck DR doubled on him when he inadvertantly set the front trigger and then pulled the rear, unset trigger. He ended up with a bloody forehead and a bent scope tube.

That same gun is now on sale by his estate at http://www.auctionarms.com/search/displayitem.cfm?itemnum=8154917. The original Lyman scope was replaced by a Leupold 1.5-5X VariX III, I believe.
The sale includes a set of 12 gauge barrels, and I think it deserves a look.

There is another Krieghoff DR which also belonged to my friend in caliber .30-'06, with interchangeable barrels in 20 gauge at http://www.auctionarms.com/search/displayitem.cfm?itemnum=8167896.