I haven't found anything different in loading for the .40 than other straight wall pistol cartridges. There is lots of data using most common pistol powders. I load for action pistol velocities using Bullseye or Promo. I have tried Unique and WW231, all with good results under the 175gr LSWC bullet. Accuracy is quite acceptable with them all, and function is 100%. That's all I need for my applications.
Savage