WOW...a neat idea that appears to have become a reality. To expand on this idea a bit, a few years back a local agricultural paper had an article in it about a box lock gun with four barrels. The gun in this article said that it was made in Ferlach, Austria by a small arms builder and could be had with either all the barrels in the same caliber/gauge or with each barrel a different caliber/gauge, including rimfire cartridges.