Magazine bans are stupid and unenforceable.The suit was about Academy selling a gun equipped with a 30 round mag. He bought the gun in Texas. But had a Colorado drivers license. 30 round mags are illegal in Colorado. I guess Academy was supposed to know that. He also bought some extra mags.but no ID is required for them.
In a free state, like Texas, a 12 year old can buy magazines. They are unregulated and are not serialized. No ID is required to buy them.
Anyone can buy them and take them to a state that bans them.
If the banning state makes the ban retroactive, they have engaged in an unlawful taking.
If they "Grandfather" existing magazines, how do they know when a magazine was made? Without serial numbers there is no way of knowing.
Unless the magazine is of a unique design that came after the ban, there is no way to know when a mag is made.