You mean people willingly want to move to California?
California has some of the most asinine gun laws in the country. I would tell him to read up carefully on what he can and cannot own in California. Hope he likes 10 round mags.
Don't forget that in 2018, Californians wont be able to buy ammo online. They will have to pay the CA DOJ for a permit just to purchase ammo in California.
California also has a roster of handguns that they wont allow into the state, but if you live there you are grandfathered in. Out of state? Nope, you need to sell it.
Best move is dont move there, unless you love to pay high taxes, high rentals, high mortgages, high insurance rates, and high fuel price, just to name a few.
Hell, Kookafornia is trying to leave the union: Its called Calexit. Look it up.