It was only $179.00 because it would not eject the cartridges. I fixed it. It is now 100% reliable. The ejector had slipped the spring collar inside. I just slipped it back into place.........and shazzam!, It works. It is the tanker version due to the hammer being removed so that the tanker could enter, move around, and exit the tank without the hammer catching on anything. It is double action only. About a 12 #lb trigger pull.