This is even more of a reaming than I thought. This is a federal judge

telling the Californicated AG he's full of shit:

The Attorney General names five additional states that enacted firing-capacity restrictions in the 1930s with capacity limits less than 10 rounds. But he is not entirely accurate. His first example is not an example, at all. For his first example, he says that, “[i]n 1933, South Dakota banned any ‘weapon from which more than five shots or bullets may be rapidly or automatically, or semi-automatically discharged from a magazine [by a single function of the firing device].’” Def’s Oppo. (4/9/18) at 4 (emphasis in original). Actually, this was not a ban. This was South Dakota’s definition of a machine gun

That is legalese for ” You got caught lying to a judge.”

The Attorney General’s second example of a longstanding firing-capacity prohibition is a Virginia ban enacted in 1934. However, like the first South Dakota example, the second example is not an example, at all. The Attorney General describes the law as a ban on firearms that discharge seven rounds rapidly. It is not ban. It also defines “machine gun.”

This one is: “You got caught lying to a judge again.”

The third cited example is like the first two. It is an Act passed by the South Carolina legislature in 1934 titled, An Act Regulating the Use and Possession of Machine Guns. Ex. E to Def.’s Request for Judicial Notice (filed 4/9/18). These three statutes are examples of machine gun bans that are prohibited because of their ability to continuously fire rounds with a single trigger pull, rather than their overall firing-capacity.

Third time is the charm.
"You either did not realize what you were quoting, or you lied about what it was." 

And on them claiming 'not in common use',
To the extent that magazines holding more than 10 rounds may be less common within California, it would likely be the result of the State long criminalizing the buying, selling, importing, and manufacturing of these magazines. Saying that large capacity magazines are uncommon because they have been banned for so long is something of a tautology. It cannot be used as constitutional support for further banning. See Friedman v. City of Highland Park, Illinois, 784 F.3d 406, 409 (7th Cir. 2015) (“Yet it would be absurd to say that the reason why a particular weapon can be banned is that there is a statute banning it, so that it isn’t commonly used. A law’s existence can’t be the source of its own constitutional validity.”

If Californicated doesn't try for the 9th Circuit, this is going to be used to whack on every state or city with such bans starting right away.  If they do go to the 9th,
9th agrees with CA, it goes to the Supremes.  Where they're likely to say "Benitez was right, deal with it."
or
9th agrees with Benitez, and Californicated and the other ban states are nailed right then.

This will be interesting.

Two more posts on the subject at GFZ here and here.