In fact, a 9mm in Wisconsin is always illegal. The DNR has designated just what a "power factor" is for a pistol, and also the barrel length. I don't mean to speak in generalities, but this means you are limited to magnum firearms with barrels of more than five inches and turn-bolt pistols of rifle calibers.
Handguns:
• To be legal for deer, handguns must use center-fire cartridges of .22 caliber or
larger and have a 5½ inch minimum barrel, measured from the iring pin to the
muzzle with the action closed.
• You may not possess a concealed handgun.
• Muzzleloading handguns, see “Muzzleloaders,” above.
• It is illegal to hunt with a handgun if under age 18