948.60 Wisconsin statute to start. Federal also applies.
Nope.
948.60(3)(c): "This section applies only to a person under 18 years of age who possesses or is armed with a rifle or a shotgun if the person is in violation of s. 941.28 or is not in compliance with ss. 29.304 and 29.593. This section applies only to an adult who transfers a firearm to a person under 18 years of age if the person under 18 years of age is not in compliance with ss. 29.304 and 29.593 or to an adult who is in violation of s. 941.28."
Since, as the prosecution conceded, Mr. Rittenhouse's rifle was not a short-barreled rifle within the meaning of s. 941.28, "this section" - i.e., 948.60 in its entirety - does not apply to Mr. Rittenhouse.