4. Any person who, prior to the effective date of this law, was legally in possession of an assault weapon or large capacity magazine shall have ninety days from such effective date to do any of the following without being subject to prosecution:
(1) Remove the assault weapon or large capacity magazine from the state of Missouri;
(2) Render the assault weapon permanently inoperable; or
(3) Surrender the assault weapon or large capacity magazine to the appropriate law enforcement agency for destruction, subject to specific agency regulations.
5. Unlawful manufacture, import, possession, purchase, sale, or transfer of an assault weapon or a large capacity magazine is a class C felony.