Abstract: A cutting insert for a gauge row of a percussion drill bit includes a generally cylindrical mounting portion extending along a central axis and a cutting head extending from the mounting portion. The cutting head has an exposed surface forming a non-symmetrical dome shape such that the working portion of the cutting head is enlarged with respect to a standard dome shape and a trailing portion of the cutting head is reduced with respect to a standard dome shape. The cutting head has an inner edge and an outer edge. The exposed surface is non-symmetrical along a central plane which bisects the working portion and the trailing portion. The exposed surface is symmetrical in a second plane perpendicular to the central plane such that the exposed surface forms an arc of constant radius from the inner edge to the outer edge in the second plane.