I waited 2 years and just gave up an bought a Texan LSS in .45. Power tuned by Hunter's Supply. Bought a variety of slugs from HS when it was tuned. With the 520 grain slugs they sell I got 779, 786 and 754 fps, which is 700.86fpe, 713.52fpe, 656.6 fpe. This is purported Hammer level performance, although not regulated.
All measured on the FX Chronograph-- which only goes to 400 grains btw (I contacted FX support asking for them allow for higher values, which was well received).