The 240 Weatherby has similar case head dimensions to the 30-06 and 308 family of cartridges, which it can handle with ease, so it should handle even maximum loads well. I'm assuming you got a rifle length barrel. If so, just pick a bullet and powder combination you want to try and try it. If you happen to have a pistol length barrel, I highly recommend bullets on the medium to light end of the weight spectrum and probably some slightly faster burning powders as well.