No. Lee makes one for the 240 weatherby mag and they have it in stock on their website240 Weatherby Custom Factory Crimp Die - Lee Precision
Each to their own but crimping will never produce as accurate ammo as no crimp, especially in bullets without a cannelure. I have never found a reason to crimp anything other than some pistol rounds and that is a taper crimp.
It is not uncommon to have the groups move with different loads. Why not adjust the scope to move the group to where you want it?
Crimping is not going to help. I would suggest that as you seated the bullet deeper into the case the group size got smaller and changed location due to barrel harmonics and not pressure.
If you want more pressure (if possible) add more powder. Have you tweaked the powder charge after you changed the seating depth?