Chuck,
I've been told by CA dealers that CA law requires a class 1 FFL for transfer of any shotgun (and I think any firearm) capable of firing a cartridge -- whether it's 50 years old, made before 1898, or whatever. I also asked the NRA at a gunshow; they didn't know and phoned an "expert" whose answer was also "not cartridge capable."
However, I've also been told by a CA dealer that he'd honor a C & R license.
I've also asked a cop, and a detective separately, questions on interpretation of CA gun laws they couldn't answer.
There's lots of confusion about CA gun laws and I don't think it's even remotely accidental. It's deplorable but I can't blame dealers for being extra-careful.