there is no way to tell just by the one story, but I figure the kid was an idiot(we actually already knoe that by default), and the gun was in his easy grasp vicinity.
16yr old dufus, small+not that strong, being an idiot, has gun real close to you: I would probably grab it too.
It would seem the BG's gun was in good working order. I have heard many times the other way around and even robberies being committed when the BG knows it probably won't shoot more than one. Of course we would always assume it would shoot a full mag no matter what we felt...we can't cut that corner.
"Damn the torpedoes, full speed ahead!" -Admiral Farragut @ Battle of Mobile Bay 05AUG1864