An interesting question. Individual states do all have their own laws regarding firearms. Even inside the individual states some municipalities also have their own laws regarding firearms. Some states like California, New York and New Jersey are pushing the envelope on controlling firearms. At present, I don't think any have attempted an outright ban on semi-auto firearms and with a ruling this past week that explicitly states that semi-automatics are not inherently weapons of war, that isn't going to help their cause. There was a case regarding 3D printed firearms that was just settled last week. The government cannot stop the production of these firearms nor the distribution of the instructions of how to do so. The limitation on them if I have it right is that they cannot be sold once produced. My state, Pennsylvania, for some unknown to me as of yet reason, decided to block the release of the instructions in the state. This is unusual because Pennsylvania is the only state which has done so and is not an anti-gun state by any means. We do have a very liberal governor and I expect is was at his urging that this happened.
What the more liberal states are doing is creating a lot of nit picky laws that make is difficult to obtain them and or use them. Magazine capacity limitations, certain features can't be on them, things like that. They've also made attempts to heavily tax ammo and the sales themselves or prohibit gun sales within their jurisdictions.
Here what has to happen is someone has to file a lawsuit claiming their 2nd Amendment rights have been violated. It then has to go through a series of courts until it is either settled or reaches the Supreme Court. The Supreme Court in the past has allowed some regulations so long as there is no outright ban but it has gotten more friendly to the 2nd Amendment in recent years. With another pro-gun nominee, this is likely to be solidified and I expect a few attempts will be made to overturn some of the regulations in the more restrictive states.
New Jersey is so bad that a person from Pennsylvania who has a license to carry and has a gun in their purse when they cross the line, if caught they will be arrested and jailed. A woman realized she made a mistake, reported it to a policeman and was immediately arrested and held for quite a long time. Not sure if it was settled yet or not. She was not a criminal by any means but New Jersey made her one. A lot of them come to PA to buy guns but are often refused. PA gun sellers have to know what is legal for NJ citizens to own before they can sell them anything. It's a bit of a mess.