We present experimental results of a high efficiency Ne-like Fe transient collisional excitation x-ray laser using the COMET 15 TW table-top laser system at LLNL. The plasma formation, ionization and collisional excitation of the x- ray laser have been optimized using two sequential laser pulses: a plasma formation beam with 5 J energy of 600 ps duration and a pump beam with 5 J energy of 1.2 ps duration. Since the observation of strong lasing on the 255 angstroms 3p - 3s J equals 0 - 1 transition of Ne-like Fe, we have achieved high gains of 35 cm-1 and saturation of the x-ray laser. A five-stage traveling wave excitation enhances the strongest Fe 3p - 3s 255 angstroms lasing line as well as additional x-ray lines. A careful characterization of the plasma column conditions using L-shell spectroscopy indicates the degree of ionization along the line focus.