A handgun has a grip portion defining a magazine well, the grip portion having a web region configured to be grasped between a thumb and an index finger, a forward portion of the web region defining a first width. The grip portion also has a palm region configured to be grasped by a user's palm, the palm region defining a second width greater than the first width. A magazine is configured to be received in the magazine well and includes a hollow magazine tube with a single-stack portion and a double-stack portion positioned below the single-stack portion. For example, front portions of the opposite tube sidewalls have a stepped shape between the upper tube end and the double-stack portion.