RAJBCPA:
Lead is not outlawed in California. There are hunting areas and portions of the state where birds of prey of prey are common where lead is not allowed even for target practice. But anywhere else in the state lead is not outlawed.
Now, some indoor ranges have use rules (and have had for decades) of no exposed lead bullets. That is to reduce lead dust indoors, in general, and lead dust being exhausted outside via fans in the range building that keep the lead dust at the firing line low. That is one of the reasons Rainier and Berrys bullets are popular here, as they are totally plated in a thin copper coating to cover the lead.
On another note, steel core ammo is a cost saving thing as steel is much cheaper than lead. The core is a thin cylinder of steel and is not the same as armor piercing ammo. Some foreign surplus ammo is steel cored.
LDBennett