The three-barreled Toz TP-82 was carried into space by Soviet and Russian cosmonauts until 2006 when the ammunition expired and it was replaced with a regular semi-automatic pistol. The top two barrels chambered 12.5x70mm (about 40 gauge) shotshells and the lower barrel chambered 5.45x39mm. A canvas covered machete was designed to be used as the stock.

Max posted this photo of it on his blog …

More info and photos here.