A monopod for a firearm is disclosed. The monopod has a body and a leg that can extend from the body. The monopod may fit into a pistol grip of a firearm, such as a rifle. Once installed, the leg of the monopod may be extended from the pistol grip of the firearm and secured by a pin. When the leg is retracted into the body, the leg is kept in place by the pin, which opposes a force provided by a constant force spring. The monopod may be used by a user to stabilize the firearm on a surface.