I am not a lawyer. Believe nothing that you read or hear (from me) without verifying it yourself unless it fits your preexisting world view.
There is no requirement to register any aspect of gun possession in Wisconsin - that I know.
I believe that a pistol may be legally transported by vehicle by boxing it unloaded.
The Wisconsin Statutes and Codes are bloated and turgid, aren't they? More than 2,000 chapters of laws telling a free people what they cannot do! Then the enforcement agencies to what they will.