Ido notcurrently owna .240 Weatherby, but have done a lot of load developomentforthe 6MM-284; which is a cartridge of very similar performance. You should do fine with the 85 grain TSX. The standard twist in a .240 Wby is 1:10. I have used 95 grain Barnes X bullets withsuccess in the 6MM-284 with a 10 twist, so stability should not be an issue with the 85 gr. H414 is the powder I would recommend. Barnes shows a maximum load of 50.0 with this powder/bullet - starting loadis 46 grains. You should top out close to 3450 fps if you have a standard Weatherby barrel with the 85 grain TSX. Please don't take my word for these recommended loads - consult the Barnes loading manual or the Barnes website. They could blow up your gun.

This bullet willshoot clear through a deer almost every time on a broadside shot. It is capable of breaking both shoulders, and can reach the vitals from some pretty steep angles. Great bullet for minimum meat damage, but may not be real immediately lethal on the broadside rib shot.

The 85 gr. Sierra HPBT Gameking is another good deer bullet in this weight. Better for rib shots, not as good for shoulder shots. Good luck. Roskoe.