You would need to go through the permit process
I believe that's incorrect, unless things have changed.
A C&R FFL, if current, allows you to purchase and receive firearms directly from the seller as long as the firearm qualifies as C&R.
Unless you register the firearm in Hawaii, you don't need anything but the C&R certificate. Just make sure you have documentation to support the firearm is C&R eligible. Plan on leaving a signed copy of your license certificate with the seller.
Firearms are required to be registered within 5 days of acquisition, so as long as you leave for home within 5 days of taking possession, you should be legal. If you plan on being in the islands longer than 5 days after transferring the firearm, then you will have to go through the registration process as a visitor.
You might also consider shipping it to your home in CA. Then you won't have to worry about an unexpected delay or scheduling problems with the seller busting the 5-day rule.
Buying and registering a C&R pistol sent straight to my home was simple. Just call HPD if you have any questions, and don't ask general questions. Be very specific about your circustances.
Aloha!
