Runner Up: DoubleTap Aluminum Handgun
This tactical gun may not look like much, but it works well for its very specific purposes: hiding in plain sight and shooting targets up to 10 feet away. When the SHTF, this is going to be a gun that you will want to have in your arsenal because it is practically unnoticeable in your pocket.
This is due to an extremely thin body that is only about the width of a finger, combined with a height of 3.9 inches and a length of 5.5 inches. The DoupleTap handgun weighs a mere 15 ounces, and it is easy to retrieve from your pocket. It is picky about bullets, so make sure you test it out before you find yourself in a life or death situation.