Hi Mike,
I have a load for my Ruger P90 that are intented for use on hogs.
255gr. LSWC & 5.0 gr. of WW231 should be a good starting point. This is quite a bit less than Speer recommends for their 260gr. JHP for the 45 ACP, but different bullet designs for SWCs will take up different amounts of room in the case. So work up carefully.
I get just under 900 fps from my gun. OAL is the longest that will feed, the shoulder of the bullet just contacts the rifling. Haven't had a chance to use it on game, unfortunately, but should be pretty good. It basically duplicates the black-powder loading in the .45Colt.