Why does Ned disobey his father when his birthday gift, the air rifle, is put away until he is older in the novel, One-Eyed Cat?

When Uncle Hilary gives Ned a Daisy air rifle for his birthday his father believes he is still too young to handle a gun, so he puts the rifle in the attic. Afterward, Ned decides that he cannot wait until he is fourteen to shoot the gun, so he sneaks the rifle out into the woods and fires it at a figure in the shadows. When Ned and Mr. Scully later see a gray cat with one eye, Ned is convinced that he is responsible for the cat's injury.