This.... There are numerous situations where you won't have the time or the ability to rack the slide. I have heard that not carrying with one on the chamber is the same as carrying a stick... This may not be completely accurate but it does apply to many (or most) situations so I never carry without one in the chamber. Make sure you invest in a good holster that covers the trigger guard and has positive retention. The example that illustrated one of these situations for me the best is sitting in a car when you are surprised by an attacker holding a knife to your neck. You will need one hand to block the knife if you can and the other to draw and shoot. Examples like this are endless... Remember, in a self defense situation you will almost always be surprised when you least expect it.