OP, with the 240XTP and your W296 (same as H110), 23 to 23.5 grains should be accurate, and also a non-event recoil wise in either of the guns you've listed. If you're looking for something a bit less energetic 12.5 of HS6 is a good load with the 240XTP, running around 1100-1150 fps - this one is a few tenths above the start load for jacketed 240's in Speer #13, and back when I could both see and hold, could keep it on an 8" plate from 60 yards off my hind legs.
None of the 3 powders you've listed are good candidates for reduced loads, especially the 300MP in my experience. At any load level below max it's more than a little bit erratic.
For other less than full throttle 44 data, the June 2006 issue of Handloader had an article that although focused on the M29, featured 3 levels of loads: Light Target, Mid-Range and Max. It's well worth tracking down the back issue.
