How could the ban have been effective at anything?

All of the grandfathered weapons AND magazines could still be sold, and any new weapons were functionally identical to the "banned" ones.

I am still pretty convinced that that aftermarket >10 round magazine production never really stopped, especially given the number of "pre-ban" undated magazines still in the wrapper for sale at reasonable cost after 2000. Yup, I am sure they are "old stock"...