Initially, Toby wants a gun because he believes that it will provide him with an identity. Shortly after, he begins dressing for the part.... the gun isn't enough, so he wears costumes that add to the illusion. The costumes, like, the gun, provide him with a sense of power, something he doesn't feel in his normal, day-to-day life. When the costumes are no longer enough, he builds a fort, in which he sits undetected, all the while keeping those in the apartment within the gun's sight. He aims, pretends to shoot, and later, decides he needs to load real bullets..... which increases the power he feels. Sadly, Toby not only feels power..... he is euphoirc, he laughs..... the thought of shooting an innocent victim brings him joy.
Over the course of the story, guns are an integral part of Toby's life. Turkey shoots, competitions, intimidation, payback... guns are a part of everything Toby does. In Vietnam, Toby uses this same sense of power to move unarmed citizens during the Vietnamese War.... loving the power and relishing their fear. Toby changes his name throughout the text for the same reason.... names provide him with what he believes to be a different identity.