A ball valve having a valve stem assembly disposed within a valve body through-hole. The valve body through-hole is encircled with secondary bores to accommodate components of the valve stem assembly. The valve stem assembly includes an upper bearing and lower bearing, which are seated into corresponding secondary bores and a stem seal that seats within a stem seal gland. The upper bearing further includes a step that interdigitates with the stem seal gland to form a stem seal groove when the valve stem assembly is disposed within the through-hole.