Hi cap magazines are banned in NY and CT, probably other states too.
The problem was, if the federal government didn’t allow them to be sold in this country, there wouldn’t be any to buy in any state. Our senators just stopped that effort. The way it is now, each state can ban them but can’t stop their being made, or imported, and being sold in other states.
I’m from Texas and we won’t ban them but they have to be allowed in the country for us to buy.