The majority Rat legislature put up SB 374 to provide Brown cover when he vetoed it for all the other firearm measures he signed. Not a good day for freedom.
I expect, aside from the occasional let er rip session, most people only have 30 rd magazines for SHTF scenarios. I’m sure most of these will just continue to sit where they are. I can’t see many people turning them in. Especially since you can claim you mailed them out of state, as the bill lists as an option.