Definitely tough to find 10 round magazines online anywhere recently. That said I went to my LGS the other day to put an M9A1 in jail and they had a variety of magazines on their shelf. Was able to buy two more for my Glock 17 and four for the M9A1 (all they had
). So you might want to shop around locally in CA and see what you can find as they are more likely to have stock.