Originally Posted by RonS
They cannot make you get rid of them. Some excerpts from various sites on the subject: Ex post facto laws are expressly forbidden by the United States Constitution in Article 1, Section 9, Clause 3 and further sections apply to the states as well. Ex post facto laws (Latin for "from after the action" or "after the fact"), also called a retroactive law, is a law that retroactively changes the legal consequences (or status) of actions that were committed, or relationships that existed, before the enactment of the law. If your state government tries to make a law and force you to get rid of your mags after you already own them then they are in direct violation of the Constitution.
Even if they did somehow get around that (not likely), they would have to get a warrant to come and take them. A warrant for each home that is. With probable cause.
Blanket warrants are also expressly forbidden.
Illegal search and seizure gets even the gun haters panties in a wad.