When purchasing parts for an AR-15 what am I allowed to have shipped directly to my home?

I live in CA (bay area) and I'm trying to buy & build a legal AR-15 but I'm not sure if the lower receiver is the only thing that I need a FFL for or not. Can I buy the lower assembly parts, bullet button magazine lock, fully assembled upper, and collapsible stock all online and shipped to my... show more I live in CA (bay area) and I'm trying to buy & build a legal AR-15 but I'm not sure if the lower receiver is the only thing that I need a FFL for or not.

Can I buy the lower assembly parts, bullet button magazine lock, fully assembled upper, and collapsible stock all online and shipped to my house?

Also if any one knows where I can get a lower receiver in the Solano County area that would be helpful.

Thanks,
Darryl
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