[John Rogers]

You would have to check with a FFL that knows the rules and have that person give a copy of whatever the CA laws say. If the buyer is out of state and not a CA resident then THAT state's FFL is in charge. If the buyer is in CA and a CA resident then the CA FFL is in charge. The magazine is probably a non issue here, sell/buy the gun without the magazine(s). There are still companies that sell magazine "parts" and you can assemble your own I.E. Black Dog sells the parts and if you want to live dangerously you can cut off the "stopper" that limits the number of rounds to 10 and the default is then 30 rounds.

These are some of the reasons why I only shoot muzzle loaders........