Some poor kid lost his BB gun in the woods (unloaded to boot) and will never find it again. It is a sad country we have become.
Yes, it's possibly a lost gun. That's hard for me to accept, though, as I still have mine (1960 vintage) with most of the finish worn off of the metal and wood. In the years of hard use I put on it, I never once lost it in the woods.
So, alternate possibility: School employee finds old BB gun at home in his closet, then hatches scheme to "find" it near the school. Our hero.