"If you know your enemies and know yourself, you can win a hundred battles without a single loss." Chinese philosopher Sun Tzu said this over 2000 years ago in his book The Art of War. It's hardly new advice. Yet it is just as useful now as it was so many centuries ago. Armed citizens spend countless hours trying to find the perfect weapon system, combining the best size, accuracy, reliability, and stopping power into one easy-to-carry package. They try friends' guns. They read gun magazines. They study every gun website on the Internet. They are truly taking Sun Tzu's...