Multi-barrel handgun firing mechanism

In a multi-barrel handgun having a frame, a barrel assembly supported on the frame and including a plurality of bores, each of the bores having an associated cartridge chamber, a hammer assembly supported on the frame for movement between tripping and striking positions and including a hammer having a bore, a firing element supported by a shaft received within the bore for indexible axial rotation on the hammer, and means for retaining the firing element in assembly with the hammer, first biasing means for normally urging the hammer assembly toward its striking position, a trigger supported on the frame for movement between ready and firing positions, means for moving the hammer from its striking position to its tripping position and releasing it in its tripping position in response to movement of the trigger from its ready to its firing position, and means for indexing the firing element to align it in firing relation to a cartridge seated in an associated one of the chambers in response to movement of the trigger toward its firing positon, the improvement wherein the retaining means includes a detent within said hammer and second biasing means for urging said detent into engagement with said shaft and comprises means for releasably retaining said firing element in assembly with said hammer and for biasing said firing element in an axial direction and into face-to-face engagement with said hammer whereby to eliminate axial play between said firing element and said hammer.