Fortunately for us, the Thompson Contender, etc. crowd have managed to make most AP rounds illegal.
The real F-ed up part about the law is if you go down to 12322 and read it, it pretty clearly states that ammunition primarily designed for rifles is exempt.
Also, the law specifically says "ammunition" and makes no mention of bullets. And, it's perfectly legal to possess it if it's been deactivated (CPC 12324)
BTW, if you shoot someone with AP rounds, it's 1st, not second degree murder. AND, if you commit a felony while armed and in possesion of AP ammo, it's an automatic 3, 4 or 10 years added onto your sentence.
Last but not least if you wear body armor while committing said felony, you get an extra 1, 2 or 5 years.
Welcome to California.
Here's the text of the law.
12320. Any person, firm, or corporation who, within this state
knowingly possesses any handgun ammunition designed primarily to
penetrate metal or armor is guilty of a public offense and upon
conviction thereof shall be punished by imprisonment in the state
prison, or in the county jail for a term not to exceed one year, or
by a fine not to exceed five thousand dollars ($5,000), or by both
such fine and imprisonment.