It is not poorly worded, it is so simple that even this humble accountant reading it found it perfectly clear.
I don't understand why this charge was even allowed.
Judge Schroeder said he had to allow it because the prosecutor followed proper procedure in submitting it to the court.
It is not inconceivable the prosecution could have introduced evidence the barrel of the rifle was 15.95 inches long, for example.
Judge Schroeder waited until the evidence was closed to make this determination.
Below is a link to the laws of Wisconsin. Lots of good active links to help navigate all of the exceptions to the rules, etc.
https://docs.legis.wisconsin.gov/statutes/statutes/948/55
948.60 Possession of a dangerous weapon by a person under 18.
(1) In this section, “dangerous weapon” means any firearm, loaded or unloaded; any electric weapon, as defined in s. 941.295 (1c) (a); metallic knuckles or knuckles of any substance which could be put to the same use with the same or similar effect as metallic knuckles; a nunchaku or any similar weapon consisting of 2 sticks of wood, plastic or metal connected at one end by a length of rope, chain, wire or leather; a cestus or similar material weighted with metal or other substance and worn on the hand; a shuriken or any similar pointed star-like object intended to injure a person when thrown; or a manrikigusari or similar length of chain having weighted ends.
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The law seems pretty clear to me that a “dangerous weapon” means any firearm. (I find it interesting that is so plainly worded, while with the other weapons they go into so much detail!)
But then later on in the exceptions they talk about target shooting with an adult, hunting, in the National Guard, etc. And then one of the exceptions is:
(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.
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The first subsection (941.28) is about the short-barreled rifles and shotguns. The other ones (29.304 and .593) pertain to hunting.
So - I would submit that the wording of the law is a bit unclear as at first they state that a dangerous weapon is ANY firearm, but then in 941.38 they state that under 18 one is only prohibited to carry a short-barreled firearm.
Perhaps they added that section - but they should have change the original(?) law to clarify short-barreled weapons.
And by the way - of course any firearm is a dangerous weapon.