Does anyone know the legality of going to California with a Handgun not on roster and ammo?  Im going to Vegas , then heading to California for a few days.  However when departing Las Vegas, i will have a handgun and ammo...Everything will be locked and not used in California before heading back to Hawaii. 

Aloha!

Don't treat this as the gospel, but my understanding from the information online at the CA gov websites is the approved list of handguns is only for guns being transferred (bought & sold, imported for sale, etc.). 

Any person transporting handguns into California is required under California law to
transport those handguns unloaded and in a locked container other than the glove compartment
or utility compartment of a vehicle.

Pursuant to California Penal Code section 25610, a United States citizen over 18 years of age
who is not prohibited from firearm possession, and who resides or is temporarily in California,
may transport by motor vehicle any handgun provided it is unloaded and locked in the vehicle’s
trunk or in a locked container. Furthermore, the handgun must be carried directly to or from any
motor vehicle for any lawful purpose and, while being carried must be contained within a locked
container.

Pursuant to California Penal Code section 16850, the term "locked container" means a secure
container that is fully enclosed and locked by a padlock, key lock, combination lock, or similar
locking device. This includes the trunk of a motor vehicle, but does not include the utility or glove
compartment.

So, as long as you have the handgun unloaded in a locked TSA-approved container, I believe you can transport it legally 

CA has no registration process for handguns non-residents own -- unlike HI.

Plenty of information out there. I'd go to the CA .gov sites first, as many of the forums have incorrect or outdated information.

I'd avoid taking any >10rd mags there even if they are "parts kits".  Illegal to "keep" hi-cap  mags for now, pending further appellate review.

https://oag.ca.gov/firearms

https://oag.ca.gov/firearms/travel

https://california.public.law/codes/ca_penal_code_section_25610

MAHALO!

that's what i found from my research also

If you have more questions you can also try calguns.net

MAHALO!