Haven't you watched the news? You can get bazookas, machine guns, and nuclear warheads without even a background check!!!!
Seriously, I don't know what the laws are in California, so I wouldn't know how it goes there, but in Georgia, you can purchase a hand gun and, after showing a concealed weapons permit which substitutes for the background check, you can walk out with it.
I'm sure a Californian can give you a better answer about how it will go there.
Just to clarify, if you don't have the permit, they just have to call in an "instant background check" that takes a few minutes..... but like I said, that's Georgia.