Stop thinking rationally.Wouldn't this also have to pass the House before becoming law? I don't know how they could even enforce something like this. From what I read it would be similar to the AWB, in that anything you owned prior to the date would be excluded from the ban. How could any government agency track who and what magazines were owned prior to the date?
This would also have a huge impact on any firearms and after-market accessories manufacturers that wanted to sell magazines in the US.