John Hare considers the capability of a monster (in more ways than one) rocket that combines a stretched SpaceX Falcon 9 with Shuttle solid rocket boosters to put about 140 tons into orbit: SFalconLS – Selenian Boondocks.
Chuck Lesher notes that Navy railgun development has reached a level of capability already sufficient to hurl small amounts of material from the Moon at escape velocities: Is the US Navy Preparing to Conquer Space? – Moonandback
Even at this early stage, the railgun is already capable of launching a 23 pound payload off the surface of the moon. We have our mass driver but getting it operational on the moon along with all the support needed to supply it with payloads… well, solving that problem must wait for another blog entry.