Percy's mother remarks that she thinks the doctor went out into the storm partly to impress Adela, and that the Colonel should take care that his daughter not grow too attached to Dr. Armstrong. Adela, hearing this, leaves the room.
That afternoon John finds Percy practicing his pistol firing skills in the garden. He sees that Percy is angry with Dr. Armstrong, and so he remarks to Percy that the doctor is very good with a pistol, able even to drive in a nail with pistol shot. Percy loses his temper and curses Dr. Armstrong, but he gives up the target practice, to John's relief.
John does not in fact know whether Dr. Armstrong can fire a pistol or not. He thinks it quite likely that he could, but in fact he does not know. I think he only made up the story about Dr. Armstrong driving nails into wood because he wanted to keep Percy from challenging the doctor to a duel.
John takes the abandoned pistol and empties the last two shots before returning it to Percy. To John's satisfaction, Percy does not return for any more target practice.
That night all the friends gather to the Colonel's house for a story from the Curate.
