It depends on the type of shooting honestly. Inner city it's likely a street gun that's been passed around it ain't exactly uncommon for middle schoolers to be walking around with guns in certain areas. The school shootings that make the news are far from the majority of shootings involving minors

The majority of legalgun owners who have guns stolen report them as stolen. The problem is most are never recovered like most stolen items. Most guns used in crimes have been either passed around multiple times and in a lot of cases have multiple homicides and shootings linked to them. Then most of them also have the serial numbers scrubbed off.

And If the gun is stolen and passed over multiple times then what

So what stops them from just going after the winner when the duel is over