An injection mold for producing a sprinkler head part and related injection molding methods are described. The sprinkler head part includes a first, second, third and fourth mold portions. The first and second mold portions include first and second shaping elements structured to cooperatively form a body including a substantially cylindrical portion and a substantially planar portion, and two frame arms extending from the substantially planar portion of the body. The third mold portion includes a shaping element structured to form an orifice in the body of the sprinkler head. The fourth mold portion includes a shaping element structured to form a cross member connecting the two frame arms. The injection methods include injecting a composite material in molten form into the mold to form the molded sprinkler head part. The composite material includes thermoplastic polymeric resin and a plurality of reinforcing fibers dispersed in the resin.