Maybe the kid thought Norm was overreacting and wanted to
get the gun away from the crazy coot before he hurt someone
else.

Rex B wrote:

On the other hand, the kid wrestled the gun away from him after he
emptied it. Presumably if he'd had more ammo the kid wouldn't have had
the chance. But if Norm got off 6 rounds and then the kid grabbed the
gun, the kid would have 9 rounds for ole Norm.