The Furious Vengeance is an ancient boltgun, that was created by master-artificers on the Rock, only a few centuries after the Horus Heresy, and although it bears no inscription, it was consecrated with terrible oaths of vengeance and retribution against traitors.
Over the millennia it has cut down many hundreds of accursed Space Marines who betrayed their Emperor and their brothers, who sold their souls to Chaos. Among its victims are a number of Fallen Dark Angels.

- From Lexicanum Entry