I’m against the feds meddling in areas that belong to the states, but IMO the 2d Amendment is a federal, Constitutional issue.
US citizens should NOT be barred from keeping and bearing arms with a patchwork of state restrictions. If I buy a gun in state A, I ought to be able to travel with it anywhere in the US without a problem.
Restricting magazine size would be, IMO, unconstitutional.
I would add that I should be able to buy a firearm in any city in America cash across the counter just like a toaster.