IMO, you need to buy and shoot lead bullets/roundballs in your pistol.
The California laws banning lead currently deal with hunters hunting in specified areas.
Read this link to get an understanding of what is actually banned and when it goes into effect.
https://www.wildlife.ca.gov/Hunting/Nonlead-Ammunition#25046244-when-does-the-nonlead-ammunition-regulation-take-effect-
There is no ban on lead bullets/balls used on recognized shooting ranges (yet) or much of the State for target shooting or plinking. (This changes after 2019)
As for getting a bullet mold just the right size for making bullets/balls for your pistol out of a non-lead alloy, as I said before, these alloys do not shrink like lead does when it solidifies so the likelihood of finding a mold that will work is slim and none.