This is not a fed action. CA registers firearms for this very reason........ so they know where to go collect them when the state so desires.
My son uses my address and is going thru a divorce. First thing his wife’s lawyer did was file a restraining order against him. First thing I did was to do a legal interfamily transfer of his guns to me.
The state DOJ still came to my door one nite, dressed like Navy Seals and wanting every gun registered to my son. They had no warrant and tried to bully their way in. I told them the guns were in my name and to go pound sand.