A shock tool (100; 200) for a drill string positionable in a wellbore, said shock tool (100; 200) comprising: an outer tubular housing having a splined housing having female multi-spiral helical spline grooves disposed on an interior surface thereof, said outer tubular housing including a lower connector for coupling to a drill bit and having a spring housing coupled to said splined housing; and an inner tubular mandrel having a portion of an exterior circumferential surface with male multi-spiral helical splines configured to mate with the female multi-spiral helical grooves of the splined housing and at least a lower portion of the exterior circumferential surface of the inner tubular mandrel not containing splines thereon, said inner tubular mandrel telescopically and rotationally received in the outer tubular housing with the male splines received in the female spline grooves of the splined housing, said lower portion of the inner tubular mandrel without splines being received in the spring housing coupled to the splined housing, said inner tubular mandrel having an axial fluid passageway for passage of drilling fluid supplied by the drill string through the inner tubular mandrel, wherein said spring housing includes at least one disc spring disposed around the lower portion of the exterior surface of the inner tubular mandrel not containing splines thereon and in an annulus between the inner tubular mandrel and an inner surface of the spring housing, said disc spring having a predetermined biasing force that biases at least a portion of the inner tubular mandrel outwardly through an axial opening in an upper end of the outer tubular housing. an outer tubular housing having a splined housing having female multi-spiral helical spline grooves disposed on an interior surface thereof, said outer tubular housing including a lower connector for coupling to a drill bit and having a spring housing coupled to said splined housing; and an inner tubular mandrel having a portion of an exterior circumferential surface with male multi-spiral helical splines configured to mate with the female multi-spiral helical grooves of the splined housing and at least a lower portion of the exterior circumferential surface of the inner tubular mandrel not containing splines thereon, said inner tubular mandrel telescopically and rotationally received in the outer tubular housing with the male splines received in the female spline grooves of the splined housing, said lower portion of the inner tubular mandrel without splines being received in the spring housing coupled to the splined housing, said inner tubular mandrel having an axial fluid passageway for passage of drilling fluid supplied by the drill string through the inner tubular mandrel, wherein said spring housing includes at least one disc spring disposed around the lower portion of the exterior surface of the inner tubular mandrel not containing splines thereon and in an annulus between the inner tubular mandrel and an inner surface of the spring housing, said disc spring having a predetermined biasing force that biases at least a portion of the inner tubular mandrel outwardly through an axial opening in an upper end of the outer tubular housing.