The rules are different for repair/service work when there is no transfer of ownership.
This is absolutely correct. The new laws in CA do not affect individuals shipping a firearm to an FFL for repair, upgrades etc...send Charley an email he will verify this. The last rifle I did came back only 3 or 4 weeks ago so I am sure about this. I asked him the same thing...
http://www.riflestockpainting.com/contact_us.html