With that bullet in my H&R single shot rifle, I got the following:
700 gr Gas Checked "Miha" mold
2.575" OAL
40.0 grs IMR-4198 (full) - 1450 fps (mid-range)
50.0 grs WC-735 (full) - 1550 fps (ouch!)
48.0 grs BLC-(2) (full) - 1200 fps (mild)
You can't put enough of those powders into the 500 S&W case with any bullet weight and exceed SAAMI pressure for the 500 S&W.