66.0409(2)
(2) Except as provided in subs. (3) and (4), no political subdivision may enact an ordinance or adopt a resolution that regulates the sale, purchase, purchase delay, transfer, ownership, use, keeping, possession, bearing, transportation, licensing, permitting, registration or taxation of any firearm or part of a firearm, including ammunition and reloader components, unless the ordinance or resolution is the same as or similar to, and no more stringent than, a state statute.
66.0409(4)(a)
(a) Nothing in this section prohibits a political subdivision from continuing to enforce an ordinance or resolution that is in effect on November 18, 1995, and that regulates the sale, purchase, transfer, ownership, use, keeping, possession, bearing, transportation, licensing, permitting, registration or taxation of any firearm or part of a firearm, including ammunition and reloader components, if the ordinance or resolution is the same as or similar to, and no more stringent than, a state statute.
66.0409(4)(b)
(b) If a political subdivision has in effect on November 17, 1995, an ordinance or resolution that regulates the sale, purchase, transfer, ownership, use, keeping, possession, bearing, transportation, licensing, permitting, registration or taxation of any firearm or part of a firearm, including ammunition and reloader components, and the ordinance or resolution is not the same as or similar to a state statute, the ordinance or resolution shall have no legal effect and the political subdivision may not enforce the ordinance or resolution on or after November 18, 1995.