yes the 10+1 refers to 10 in the mag and one in the guns chamber and it is legal in CA

Did my time in California, and you have my sympathies. The XX+1 refers to a full magazine + 1 in the chamber. As to "High" capacity, that is a misnomer. 17 and 18 round magazines are standard capacity and 10 round magazines are low or truncated capacity. The manufacturer actually has to put a limiter in the magazine so that you can't hold the full capacity of your magazine.

Not sure as all us Southern boys have LARGE Mags !

Rick, yes Sir. Restricted States only count the Magazine capacity and not the chambered round. So a rifle or handgun with a round in the chamber and full 10 round magazine (11 rounds total) is still perfectly legal.

Yes it means the same. Because the 10+1 means 10 rounds in magazine and 1 round in chamber.