I know in here in California it comes down to magazine capacity. Myself and all other non Law Enforcement types are restricted to 10 rounds or less. There are also firearms you can buy in other states and not California. Firearms in California have to be certified to be sold in California. The state actually has a list of firearms that make the list.
My co-workers and I are full time Firefighters (normally I would not even mention that, but it does relate to the story).
One of my co-workers went to buy a Glock 40cal exact model I forget may have been 23. Because he was not law enforcement they sold one to him, but they took $60.00 off the price and took away both magazines. It took him 2 months to find 2 10 round magazines for his Glock.
So a month after that, a station down the street from mine, got a flier from Glock on the Blue Label program. So 2 Firefighters from that station and 1 from mine go to the participating store and order Glocks.
I did not, I was afraid of getting a firearm with no magazines. So they pay 100% up front and have to wait. About a month or two later they are told they may or may not get magazines, but the store would make price adjustments if necessary. 2 months after that, they are told to come in and they will be refunded 100% of their money.
Turns out the Glocks on the blue label program are made in Austria, not assembled in GA. Same glock, just different manufacture point.
Those Glocks are not California Legal, only because it does not have the Symra GA on it, It only says Austria. Those have not been California approved. It all comes down to a stupid engraved stamp.
So that whole process took about 4 months. Now is that true about the Symra GA vs Austria? I am not sure, but that is what they were told by the Gun store they did the order at.