Yes.

Uppers are not regulated.

Lowers are.

10 round fixed magazine lowers are not.

There is a metric butt ton of off list lowers that are not regulated, available, which can't be built into a full functional rifle until the DOJ puts them on the list, you register them as an assualt weapon and the you can build them into a fully functional weapon.

Dig in and read the post pinned to the top of the formum - California weapons primer.

Please don't come here - the roads are full, housing is expensive, it's too hot, the air is polluted, the women are really ugly, the job market sucks ....