The 2nd Amendment applies to All Americans, but it was intended to limit a possible Federal threat. It was not directed towards the States. You may be able to get a Court today, to consider a 14th Amendment attack on the California restrictions, but I would not count on it.
Frankly, I do not believe that any State can legally prohibit its citizens from having guns for self-protection. But my argument there would come under the fundamental concept of Republican Government as a compact. Since there is no way that the State can adequately protect its citizens from all threats, disarming them is tantamount to violating the compact to secure life, liberty and the pursuit of happiness, as set forth in our justification for ending British Government here.
-- Art. IV, which you quoted, says in Sec 2 that citizens in every state shall be entitled to the same 'priviliges & immunities'. What does that mean to you?
It means that if you come to Ohio from California, you will be entitled to all of the rights and privileges of an Ohioan, under our law. (This was not intended, however, to confer automatic voting privileges. And the ridiculously short residency requirements to vote in any State, today--a result of the Leftwing Activist Judiciary of a few years ago--is something that needs to be addressed.) In other words you can own property, drive under the conditions set down for Ohioans, drink whatever Ohioans can drink, and have full access and fair treatment in our Courts, etc..
-- And, Sec. 4 says that every state shall have a Republican Form of Government. Can a Republican State prohibit certain types of self defense weapons from its citizens?
It cannot effectively disarm them, under the argument that I used above. Under the Police power, it may or may not be able to ban certain devices. The Police power, which remains with the States--it was not delegated to the Federal Government--is very broad. But, generally, in a free State it must be exercised reasonably--not capriciously or in a purely arbitrary manner. Those are questions that would have to be addressed in assessing any attempted regulation.
William Flax