First I try to make sure the bullet fits,next come the hardness depending on what I'm shooting the bullet in and at what velocity. For plain base bullets I like a mix of 50/50 WW/Lead for low velocity stuff. For mid range loads around 1200 fps. in 357 mag. pistol and 30-30 plinking loads I use straight AC WW.

sometime I water quench them as well doesn't seem to make any difference and for the 30-30 plinking loads I leave the gas check off didn't make any differance in accuracy that I could tell.

Now when I step up the 357 loads I like either a gas checked bullet which I can cast softer or water quench the plan base bullet for sure. I also use a gas check on the 30-30,300 Sav,7.62 x 39 and 54r bullets because I'm shooting them somewhat close to there original factory jacketed velocity. Gas check allow me to cast the bullet softer I find a 30:1 Lead/Tin mix gives decent expansion with FN bullets at mid range velocities.

On the X39 which is a semi-auto I water quench or heat treat them,the extra hardness helps keep the bullet from getting damaged when transitioning from the magazine into the chamber. Not sure if there are any available but a good gas checked HP design would give you some good expansion.