I fired my new-to-me 8 3/8" S&W .500 last weekend with twenty rounds of Corbon ammo loaded with 265 bullets, and really liked it.
Today I tried two different handloads; a plain base 335 gr. at approx. 1100 fps with Blue Dot, and a 400 gr. gas check at approximately 1250 with IMR 4227. The gun handled both loads well, accuracy seemed fine, and recoils and blast were within my personal tolerances, even with the heavier load. I used Federal Std. rifle primers with both loads.
The only note of concern was the ejector star not picking up one of the empty cartridges three or four times, with the lighter load. It was easy enough to clear the problem as the brass wasn't sticking. Any suggestions on a cause or a cure on that would be appreciated.