Mare's Leg is a special kind of gun that looks like something out of a cowboy movie. It's a rifle that's been cut down so it only has a pistol handle and a short barrel. It was made popular by the TV show "The Rifleman" in the 1950s, where the main character, Lucas McCain, would use it to shoot bad guys. Mare's Leg is illegal in some places, so it's not a good idea to try to buy one.