Abstract: A gun device for driving a fixing element into a work surface includes a driving mechanism for the fixing element. The gun device further includes supply means for a filler material, the supply means having an outlet arranged to deposit filler material on the work surface at a point corresponding substantially to an entry point of the fixing element into the work surface. Actuating means is provided for actuating the supply means in response to advancement of the gun device towards the work surface to deposit filler material on the work surface. Movable means is provided, movable in response to retreat of the gun device from the work surface, to pass across the work surface over the end of the fixing element so as to cause deposited filler material to smooth and fill any depression formed in the work surface as a result of operation of the gun device.