To Kill A Mocking Bird Chapters 12, 13, 14

Ok, So around the end of chapter 13, Atticus has was explaining to Jem how he and Scout were the product of several generations of gentle breeding, and that there family were a gentle breed. If so, then why is Atticus so good with firearms? Surely he couldn't have been born being the best shot in the country, so he must have practiced. But why was he practicing with guns if he was such a "gentle breed"? Not to mention that Atticus is completely OK with his "gentle-breed children" to shoot all the birds they want (except mocking birds of course) with their air rifles. I think that Atticus was exaggerating about their gentle family.