from personal experience, different FFLs have their own set of "rules" (or maybe just different interpretations of the law).
a few months back, i wanted to private party transfer 3 handguns to my name. the first FFL i went to REFUSED to do it, saying it was illegal (only 1/month he says). i informed him that CA law only limits NEW handgun purchases to 1/month (no limit on private transfers). he replied, "the law is the law and we obey ALL laws!" after showing him the HSC booklet to back-up my argument, he still refused. whatevers, i went somewhere else...
the 2nd FFL gladly processed all 3 transfers and asked me for my safe info. all i needed to provide was Make & Model Number on a signed affidavit. if i did not have a safe, i wouldve had to provide a receipt of newly purchased locks (dated within 30 days). if receipt was older than that, then i'd be required to buy all new locks. no requirement of receipt for a safe (only for lock).