Embodiments of golf club heads and methods to manufacture golf club heads are generally described herein. In one example, a golf club head may include a face portion having a front surface and a back surface with a plurality of back surface grooves. Each back surface groove includes a groove opening with a groove opening width and an interior groove width at a location inside the back surface groove. The interior groove width is greater than the groove opening width. The golf club head further includes a body portion and an interior cavity enclosed by coupling the face portion and the body portion, a port connected to the interior cavity; and a polymer material injected into the interior cavity from the port and filling the plurality of back surface grooves. Other examples and embodiments may be described and claimed.