A fastener driving tool having a reciprocating driver blade and a nosepiece, and being configured for sequentially feeding fasteners to the nosepiece for engagement by the driver blade for subsequent driving into a workpiece, each fastener defining a plane, further includes a deformation formation in the nosepiece configured for engaging a portion of each of the fasteners so that upon impact of the fastener by the driver blade, the engaged fastener portion is deformed in a direction transverse to the plane to define a deformed portion, the deformed portion configured for providing a clamping force upon at least one of the workpiece and a workpiece material being secured to the workpiece. A fastener is provided for use in such a tool and includes a crown configured so that, upon impact with at least one of the workpiece and the workpiece material, the crown has a nonlinear configuration.