Gavin Newsom signed a slew of new gun regulations into law yesterday.
One of the bills signed was AB 879.
Bill Text - AB-879 Firearms.
You will need a "firearm precursor parts license" from the state to sell a gun part that the CA DOJ deems a precursor part. Also makes it illegal to sell any precursor part to someone under the age of 21 and all transactions have to go through a FFL and a background check will need to be done, $1 if you have a gun registered to the address that's listed on your drivers license and $15 if you do not
(which from then on you'll be on record and any new purchases and you can then use the $1 for the DROS). Doesn't go into effect until 2024.
So anyone who wants to customize there firearm they already own or wants to replace a broken part will be subjected to extra fees and wait times.