On the DNR website it does have a link to the public land in WI. There are thousands of acres open but much of it gets hunted hard especially around the cities and south and west of Madison as that's open for rifle hunting. Right next to you in both Sauk and Columbia counties much of the land by the WI river is public land and you can use a rifle there. Take a drive along the WI river roads and you'll see quite a few of the signs for public ground, they are usually white/green or brown/white.