Give one text based detail to support your thought.
I think it was because Atticus didn't want the kids to brag about their skills? But I couldn't find a quote..
It definitely has to do with Atticus's revulsion to violence. Atticus represents the good in human nature. Atticus believed that people have the ability to work things out if only they showed a bit of compassion and understanding. Guns were a symbol of violence and inability to compromise, "real courage is -- not a man with a gun in his hand but someone who faces ...." Scout and Jem are still kids and Atticus feels that they deserve time without guns in their lives.
